diff --git a/packages/cart/integration-tests/__tests__/services/cart-module/index.spec.ts b/packages/cart/integration-tests/__tests__/services/cart-module/index.spec.ts
index ac66ef2d20eb7..3148d14b2d597 100644
--- a/packages/cart/integration-tests/__tests__/services/cart-module/index.spec.ts
+++ b/packages/cart/integration-tests/__tests__/services/cart-module/index.spec.ts
@@ -481,14 +481,14 @@ describe("Cart Module Service", () => {
       const error = await service
         .addLineItems(createdCart.id, [
           {
-            quantity: 1,
+            unit_price: 10,
             title: "test",
           },
         ] as any)
         .catch((e) => e)
 
       expect(error.message).toContain(
-        "Value for LineItem.unit_price is required, 'undefined' found"
+        "Value for LineItem.quantity is required, 'undefined' found"
       )
     })
 
@@ -503,14 +503,14 @@ describe("Cart Module Service", () => {
         .addLineItems([
           {
             cart_id: createdCart.id,
-            quantity: 1,
+            unit_price: 10,
             title: "test",
           },
         ] as any)
         .catch((e) => e)
 
       expect(error.message).toContain(
-        "Value for LineItem.unit_price is required, 'undefined' found"
+        "Value for LineItem.quantity is required, 'undefined' found"
       )
     })
   })
diff --git a/packages/cart/src/migrations/CartModuleSetup20240122122952.ts b/packages/cart/src/migrations/CartModuleSetup20240122122952.ts
index cea797ef6881d..c178fb50c10a8 100644
--- a/packages/cart/src/migrations/CartModuleSetup20240122122952.ts
+++ b/packages/cart/src/migrations/CartModuleSetup20240122122952.ts
@@ -80,7 +80,9 @@ export class CartModuleSetup20240122122952 extends Migration {
       "is_discountable" BOOLEAN NOT NULL DEFAULT TRUE,
       "is_tax_inclusive" BOOLEAN NOT NULL DEFAULT FALSE,
       "compare_at_unit_price" NUMERIC NULL,
+      "raw_compare_at_unit_price" JSONB NULL,
       "unit_price" NUMERIC NOT NULL,
+      "raw_unit_price" JSONB NOT NULL,
       "created_at" TIMESTAMPTZ NOT NULL DEFAULT NOW(),
       "updated_at" TIMESTAMPTZ NOT NULL DEFAULT NOW(),
       CONSTRAINT "cart_line_item_pkey" PRIMARY KEY ("id"),
@@ -134,6 +136,7 @@ export class CartModuleSetup20240122122952 extends Migration {
       "name" TEXT NOT NULL,
       "description" JSONB NULL,
       "amount" NUMERIC NOT NULL,
+      "raw_amount" JSONB NOT NULL,
       "is_tax_inclusive" BOOLEAN NOT NULL DEFAULT FALSE,
       "shipping_option_id" TEXT NULL,
       "data" JSONB NULL,
diff --git a/packages/cart/src/models/line-item.ts b/packages/cart/src/models/line-item.ts
index 5ab63a65651a4..2cc4dc87acdce 100644
--- a/packages/cart/src/models/line-item.ts
+++ b/packages/cart/src/models/line-item.ts
@@ -1,9 +1,9 @@
-import { DAL } from "@medusajs/types"
-import { generateEntityId } from "@medusajs/utils"
+import { BigNumberRawValue, DAL } from "@medusajs/types"
+import { BigNumber, generateEntityId } from "@medusajs/utils"
 import {
   BeforeCreate,
+  BeforeUpdate,
   Cascade,
-  Check,
   Collection,
   Entity,
   ManyToOne,
@@ -109,12 +109,16 @@ export default class LineItem {
   is_tax_inclusive = false
 
   @Property({ columnType: "numeric", nullable: true })
-  compare_at_unit_price: number | null = null
+  compare_at_unit_price?: BigNumber | number | null = null
 
-  // TODO: Rework when BigNumber has been introduced
-  @Property({ columnType: "numeric", serializer: Number })
-  @Check({ expression: "unit_price >= 0" }) // TODO: Validate that numeric types work with the expression
-  unit_price: number
+  @Property({ columnType: "jsonb", nullable: true })
+  raw_compare_at_unit_price: BigNumberRawValue | null = null
+
+  @Property({ columnType: "numeric" })
+  unit_price: BigNumber | number
+
+  @Property({ columnType: "jsonb" })
+  raw_unit_price: BigNumberRawValue
 
   @OneToMany(() => LineItemTaxLine, (taxLine) => taxLine.item, {
     cascade: [Cascade.REMOVE],
@@ -144,10 +148,28 @@ export default class LineItem {
   @BeforeCreate()
   onCreate() {
     this.id = generateEntityId(this.id, "cali")
+
+    const val = new BigNumber(this.raw_unit_price ?? this.unit_price)
+
+    this.unit_price = val.numeric
+    this.raw_unit_price = val.raw!
+  }
+
+  @BeforeUpdate()
+  onUpdate() {
+    const val = new BigNumber(this.raw_unit_price ?? this.unit_price)
+
+    this.unit_price = val.numeric
+    this.raw_unit_price = val.raw as BigNumberRawValue
   }
 
   @OnInit()
   onInit() {
     this.id = generateEntityId(this.id, "cali")
+
+    const val = new BigNumber(this.raw_unit_price ?? this.unit_price)
+
+    this.unit_price = val.numeric
+    this.raw_unit_price = val.raw!
   }
 }
diff --git a/packages/cart/src/models/shipping-method.ts b/packages/cart/src/models/shipping-method.ts
index c3a2ed448a421..9daa2a1580c8f 100644
--- a/packages/cart/src/models/shipping-method.ts
+++ b/packages/cart/src/models/shipping-method.ts
@@ -1,4 +1,5 @@
-import { generateEntityId } from "@medusajs/utils"
+import { BigNumberRawValue } from "@medusajs/types"
+import { BigNumber, generateEntityId } from "@medusajs/utils"
 import {
   BeforeCreate,
   Cascade,
@@ -11,6 +12,7 @@ import {
   PrimaryKey,
   Property,
 } from "@mikro-orm/core"
+import { BeforeUpdate } from "typeorm"
 import Cart from "./cart"
 import ShippingMethodAdjustment from "./shipping-method-adjustment"
 import ShippingMethodTaxLine from "./shipping-method-tax-line"
@@ -37,8 +39,11 @@ export default class ShippingMethod {
   @Property({ columnType: "jsonb", nullable: true })
   description: string | null = null
 
-  @Property({ columnType: "numeric", serializer: Number })
-  amount: number
+  @Property({ columnType: "numeric" })
+  amount: BigNumber | number
+
+  @Property({ columnType: "jsonb" })
+  raw_amount: BigNumberRawValue
 
   @Property({ columnType: "boolean" })
   is_tax_inclusive = false
@@ -92,10 +97,28 @@ export default class ShippingMethod {
   @BeforeCreate()
   onCreate() {
     this.id = generateEntityId(this.id, "casm")
+
+    const val = new BigNumber(this.raw_amount ?? this.amount)
+
+    this.amount = val.numeric
+    this.raw_amount = val.raw!
+  }
+
+  @BeforeUpdate()
+  onUpdate() {
+    const val = new BigNumber(this.raw_amount ?? this.amount)
+
+    this.amount = val.numeric
+    this.raw_amount = val.raw as BigNumberRawValue
   }
 
   @OnInit()
   onInit() {
     this.id = generateEntityId(this.id, "casm")
+
+    const val = new BigNumber(this.raw_amount ?? this.amount)
+
+    this.amount = val.numeric
+    this.raw_amount = val.raw!
   }
 }
diff --git a/packages/cart/src/services/cart-module.ts b/packages/cart/src/services/cart-module.ts
index 79274eed6b21d..5d404950cbbd1 100644
--- a/packages/cart/src/services/cart-module.ts
+++ b/packages/cart/src/services/cart-module.ts
@@ -11,11 +11,11 @@ import {
 import {
   InjectManager,
   InjectTransactionManager,
-  isObject,
-  isString,
   MedusaContext,
   MedusaError,
   ModulesSdkUtils,
+  isObject,
+  isString,
 } from "@medusajs/utils"
 import {
   Address,
diff --git a/packages/cart/src/services/index.ts b/packages/cart/src/services/index.ts
index 2ed2053ffcb36..440fec6e50ba9 100644
--- a/packages/cart/src/services/index.ts
+++ b/packages/cart/src/services/index.ts
@@ -1 +1 @@
-export { default as CartModuleService } from "./cart-module"
+export { default as CartModuleService } from "./cart-module";
diff --git a/packages/cart/src/types/line-item.ts b/packages/cart/src/types/line-item.ts
index b7fd239713a72..caf407251057e 100644
--- a/packages/cart/src/types/line-item.ts
+++ b/packages/cart/src/types/line-item.ts
@@ -26,7 +26,7 @@ interface PartialUpsertLineItemDTO {
 export interface CreateLineItemDTO extends PartialUpsertLineItemDTO {
   title: string
   quantity: number
-  unit_price: number
+  unit_price: number | string
   cart_id: string
 }
 
diff --git a/packages/medusa/src/services/new-totals.ts b/packages/medusa/src/services/new-totals.ts
index b81215a6eb900..9df49230b0cc7 100644
--- a/packages/medusa/src/services/new-totals.ts
+++ b/packages/medusa/src/services/new-totals.ts
@@ -79,8 +79,8 @@ export default class NewTotalsService extends TransactionBaseService {
 
   /**
    * Calculate and return the items totals for either the legacy calculation or the new calculation
-   * @param items 
-   * @param param1 
+   * @param items
+   * @param param1
    */
   async getLineItemTotals(
     items: LineItem | LineItem[],
@@ -136,9 +136,9 @@ export default class NewTotalsService extends TransactionBaseService {
 
   /**
    * Calculate and return the totals for an item
-   * @param item 
-   * @param param1 
-   * @returns 
+   * @param item
+   * @param param1
+   * @returns
    */
   protected async getLineItemTotals_(
     item: LineItem,
diff --git a/packages/payment/src/models/capture.ts b/packages/payment/src/models/capture.ts
index f0d5be2a25cf8..643cc01acf918 100644
--- a/packages/payment/src/models/capture.ts
+++ b/packages/payment/src/models/capture.ts
@@ -1,3 +1,4 @@
+import { generateEntityId } from "@medusajs/utils"
 import {
   BeforeCreate,
   Entity,
@@ -7,8 +8,6 @@ import {
   PrimaryKey,
   Property,
 } from "@mikro-orm/core"
-
-import { generateEntityId } from "@medusajs/utils"
 import Payment from "./payment"
 
 type OptionalCaptureProps = "created_at"
diff --git a/packages/types/package.json b/packages/types/package.json
index 10d22d6f62395..3e342990f9486 100644
--- a/packages/types/package.json
+++ b/packages/types/package.json
@@ -22,6 +22,7 @@
   "license": "MIT",
   "devDependencies": {
     "awilix": "^8.0.0",
+    "bignumber.js": "^9.1.2",
     "cross-env": "^5.2.1",
     "ioredis": "^5.2.5",
     "rimraf": "^5.0.1",
diff --git a/packages/types/src/cart/common.ts b/packages/types/src/cart/common.ts
index b83c2b7d6d514..2fb47b3fe2417 100644
--- a/packages/types/src/cart/common.ts
+++ b/packages/types/src/cart/common.ts
@@ -261,7 +261,23 @@ export interface CartShippingMethodDTO {
   discount_tax_total: number
 }
 
-export interface CartLineItemDTO {
+export interface CartLineItemTotalsDTO {
+  original_total: number
+  original_subtotal: number
+  original_tax_total: number
+
+  item_total: number
+  item_subtotal: number
+  item_tax_total: number
+
+  total: number
+  subtotal: number
+  tax_total: number
+  discount_total: number
+  discount_tax_total: number
+}
+
+export interface CartLineItemDTO extends CartLineItemTotalsDTO {
   /**
    * The ID of the line item.
    */
@@ -384,20 +400,6 @@ export interface CartLineItemDTO {
    * When the line item was updated.
    */
   updated_at?: Date
-
-  original_total: number
-  original_subtotal: number
-  original_tax_total: number
-
-  item_total: number
-  item_subtotal: number
-  item_tax_total: number
-
-  total: number
-  subtotal: number
-  tax_total: number
-  discount_total: number
-  discount_tax_total: number
 }
 
 export interface CartDTO {
@@ -478,8 +480,12 @@ export interface CartDTO {
   subtotal: number
   tax_total: number
   discount_total: number
+  raw_discount_total: any
   discount_tax_total: number
 
+  gift_card_total: number
+  gift_card_tax_total: number
+
   shipping_total: number
   shipping_subtotal: number
   shipping_tax_total: number
diff --git a/packages/types/src/cart/mutations.ts b/packages/types/src/cart/mutations.ts
index 25d0dc71728d1..dc4ea41016531 100644
--- a/packages/types/src/cart/mutations.ts
+++ b/packages/types/src/cart/mutations.ts
@@ -156,7 +156,7 @@ export interface CreateLineItemDTO {
   is_tax_inclusive?: boolean
 
   compare_at_unit_price?: number
-  unit_price: number
+  unit_price: number | string
 
   tax_lines?: CreateTaxLineDTO[]
   adjustments?: CreateAdjustmentDTO[]
diff --git a/packages/types/src/index.ts b/packages/types/src/index.ts
index 5d7d823b6e9e7..ab086b109dab3 100644
--- a/packages/types/src/index.ts
+++ b/packages/types/src/index.ts
@@ -26,6 +26,7 @@ export * from "./sales-channel"
 export * from "./search"
 export * from "./shared-context"
 export * from "./stock-location"
+export * from "./totals"
 export * from "./transaction-base"
 export * from "./user"
 export * from "./workflow"
diff --git a/packages/types/src/totals/big-number.ts b/packages/types/src/totals/big-number.ts
new file mode 100644
index 0000000000000..1a0740d154577
--- /dev/null
+++ b/packages/types/src/totals/big-number.ts
@@ -0,0 +1,12 @@
+import BigNumber from "bignumber.js"
+
+export type BigNumberRawValue = {
+  value: string | number
+  [key: string]: unknown
+}
+
+export type BigNumberRawPriceInput =
+  | BigNumberRawValue
+  | number
+  | string
+  | BigNumber
diff --git a/packages/types/src/totals/index.ts b/packages/types/src/totals/index.ts
new file mode 100644
index 0000000000000..0ed2463b75015
--- /dev/null
+++ b/packages/types/src/totals/index.ts
@@ -0,0 +1,2 @@
+export * from "./big-number";
+
diff --git a/packages/utils/package.json b/packages/utils/package.json
index 8ffbf885ea8a6..9d9fcbdbe8532 100644
--- a/packages/utils/package.json
+++ b/packages/utils/package.json
@@ -35,6 +35,7 @@
     "@mikro-orm/migrations": "5.9.7",
     "@mikro-orm/postgresql": "5.9.7",
     "awilix": "^8.0.1",
+    "bignumber.js": "^9.1.2",
     "knex": "2.4.2",
     "ulid": "^2.3.0"
   },
diff --git a/packages/utils/src/common/index.ts b/packages/utils/src/common/index.ts
index 2c8a76c74eac8..85e47879eefa7 100644
--- a/packages/utils/src/common/index.ts
+++ b/packages/utils/src/common/index.ts
@@ -14,6 +14,7 @@ export * from "./get-iso-string-from-date"
 export * from "./get-selects-and-relations-from-object-array"
 export * from "./group-by"
 export * from "./handle-postgres-database-error"
+export * from "./is-big-number"
 export * from "./is-date"
 export * from "./is-defined"
 export * from "./is-email"
diff --git a/packages/utils/src/common/is-big-number.ts b/packages/utils/src/common/is-big-number.ts
new file mode 100644
index 0000000000000..8335b649ed93c
--- /dev/null
+++ b/packages/utils/src/common/is-big-number.ts
@@ -0,0 +1,6 @@
+import { BigNumberRawValue } from "@medusajs/types"
+import { isObject } from "./is-object"
+
+export function isBigNumber(obj: any): obj is BigNumberRawValue {
+  return isObject(obj) && "value" in obj
+}
diff --git a/packages/utils/src/index.ts b/packages/utils/src/index.ts
index 814ab3a098775..bf8953ef387d6 100644
--- a/packages/utils/src/index.ts
+++ b/packages/utils/src/index.ts
@@ -16,5 +16,7 @@ export * from "./product"
 export * from "./promotion"
 export * from "./search"
 export * from "./shipping"
+export * from "./totals"
+export * from "./totals/big-number"
 
 export const MedusaModuleType = Symbol.for("MedusaModule")
diff --git a/packages/utils/src/totals/__tests__/big-number.spec.ts b/packages/utils/src/totals/__tests__/big-number.spec.ts
new file mode 100644
index 0000000000000..7fd7702f4d040
--- /dev/null
+++ b/packages/utils/src/totals/__tests__/big-number.spec.ts
@@ -0,0 +1,36 @@
+import { BigNumber as BN } from "bignumber.js"
+import { BigNumber } from "../big-number"
+
+describe("BigNumber", function () {
+  describe("constructor", function () {
+    it("should set and return number", function () {
+      const number = new BigNumber(42)
+      expect(JSON.stringify(number)).toEqual(JSON.stringify(42))
+    })
+
+    it("should set BigNumber and return number", function () {
+      const number = new BigNumber({
+        value: "42",
+      })
+      expect(JSON.stringify(number)).toEqual(JSON.stringify(42))
+    })
+
+    it("should set string and return number", function () {
+      const number = new BigNumber("42")
+      expect(JSON.stringify(number)).toEqual(JSON.stringify(42))
+    })
+
+    it("should set bignumber.js and return number", function () {
+      const bn = new BN("42")
+      const number = new BigNumber(bn)
+      expect(JSON.stringify(number)).toEqual(JSON.stringify(42))
+    })
+
+    it("should throw if not correct type", function () {
+      // @ts-ignore
+      expect(() => new BigNumber([])).toThrow(
+        "Invalid BigNumber value. Should be one of: string, number, BigNumber (bignumber.js), BigNumberRawValue"
+      )
+    })
+  })
+})
diff --git a/packages/utils/src/totals/big-number.ts b/packages/utils/src/totals/big-number.ts
new file mode 100644
index 0000000000000..623d967eff1cd
--- /dev/null
+++ b/packages/utils/src/totals/big-number.ts
@@ -0,0 +1,97 @@
+import { BigNumberRawPriceInput, BigNumberRawValue } from "@medusajs/types"
+import { BigNumber as BigNumberJS } from "bignumber.js"
+import { isBigNumber, isString } from "../common"
+
+export class BigNumber {
+  static DEFAULT_PRECISION = 20
+
+  private numeric_: number
+  private raw_?: BigNumberRawValue
+
+  constructor(rawPrice: BigNumberRawPriceInput) {
+    this.setRawPriceOrThrow(rawPrice)
+  }
+
+  setRawPriceOrThrow(rawPrice: BigNumberRawPriceInput) {
+    if (BigNumberJS.isBigNumber(rawPrice)) {
+      /**
+       * Example:
+       *  const bnUnitPrice = new BigNumberJS("10.99")
+       *  const unitPrice = new BigNumber(bnUnitPrice)
+       */
+      this.numeric_ = rawPrice.toNumber()
+      this.raw_ = {
+        value: rawPrice.toPrecision(BigNumber.DEFAULT_PRECISION),
+      }
+    } else if (isString(rawPrice)) {
+      /**
+       * Example: const unitPrice = "1234.1234"
+       */
+      const bigNum = new BigNumberJS(rawPrice)
+
+      this.numeric_ = bigNum.toNumber()
+      this.raw_ = this.raw_ = {
+        value: bigNum.toPrecision(BigNumber.DEFAULT_PRECISION),
+      }
+    } else if (isBigNumber(rawPrice)) {
+      /**
+       * Example: const unitPrice = { value: "1234.1234" }
+       */
+      this.numeric_ = BigNumberJS(rawPrice.value).toNumber()
+
+      this.raw_ = {
+        ...rawPrice,
+      }
+    } else if (typeof rawPrice === `number` && !Number.isNaN(rawPrice)) {
+      /**
+       * Example: const unitPrice = 1234
+       */
+      this.numeric_ = rawPrice as number
+
+      this.raw_ = {
+        value: BigNumberJS(rawPrice as number).toString(),
+      }
+    } else {
+      throw new Error(
+        "Invalid BigNumber value. Should be one of: string, number, BigNumber (bignumber.js), BigNumberRawValue"
+      )
+    }
+  }
+
+  get numeric(): number {
+    let raw = this.raw_ as BigNumberRawValue
+    if (raw) {
+      return new BigNumberJS(raw.value).toNumber()
+    } else {
+      return this.numeric_
+    }
+  }
+
+  set numeric(value: BigNumberRawPriceInput) {
+    const newValue = new BigNumber(value)
+    this.numeric_ = newValue.numeric_
+    this.raw_ = newValue.raw_
+  }
+
+  get raw(): BigNumberRawValue | undefined {
+    return this.raw_
+  }
+
+  set raw(rawValue: BigNumberRawPriceInput) {
+    const newValue = new BigNumber(rawValue)
+    this.numeric_ = newValue.numeric_
+    this.raw_ = newValue.raw_
+  }
+
+  toJSON() {
+    return this.raw_
+      ? new BigNumberJS(this.raw_.value).toNumber()
+      : this.numeric_
+  }
+
+  valueOf() {
+    return this.raw_
+      ? new BigNumberJS(this.raw_.value).toNumber()
+      : this.numeric_
+  }
+}
diff --git a/packages/utils/src/totals/index.ts b/packages/utils/src/totals/index.ts
new file mode 100644
index 0000000000000..260851b0b2aa5
--- /dev/null
+++ b/packages/utils/src/totals/index.ts
@@ -0,0 +1,235 @@
+import {
+  BigNumberRawValue,
+  CartDTO,
+  CartShippingMethodDTO,
+} from "@medusajs/types"
+import { BigNumber as BigNumberJs } from "bignumber.js"
+import { BigNumber } from "./big-number"
+import { toBigNumberJs } from "./to-big-number-js"
+
+type GetLineItemTotalsContext = {
+  includeTax?: boolean
+  taxRate?: number | null
+}
+
+interface GetShippingMethodTotalInput extends CartShippingMethodDTO {
+  raw_amount: BigNumberRawValue
+}
+
+interface GetItemTotalInput {
+  id: string
+  unit_price: BigNumber
+  quantity: number
+  is_tax_inclusive?: boolean
+  tax_total?: BigNumber
+  original_tax_total?: BigNumber
+}
+
+interface GetItemTotalOutput {
+  quantity: number
+  unit_price: BigNumber
+
+  subtotal: BigNumber
+  total: BigNumber
+  original_total: BigNumber
+  discount_total: BigNumber
+  tax_total: BigNumber
+  original_tax_total: BigNumber
+}
+
+export function getShippingMethodTotals(
+  shippingMethods: GetShippingMethodTotalInput[],
+  context: { includeTax?: boolean }
+) {
+  const { includeTax } = context
+
+  const shippingMethodsTotals = {}
+
+  for (const shippingMethod of shippingMethods) {
+    shippingMethodsTotals[shippingMethod.id] = getShippingMethodTotals_(
+      shippingMethod,
+      {
+        includeTax,
+      }
+    )
+  }
+
+  return shippingMethodsTotals
+}
+
+export function getShippingMethodTotals_(
+  shippingMethod: GetShippingMethodTotalInput,
+  context: { includeTax?: boolean }
+) {
+  const { amount, taxTotal, originalTaxTotal } = toBigNumberJs(shippingMethod, [
+    "amount",
+    "tax_total",
+    "original_tax_total",
+  ])
+
+  const amountBn = new BigNumber(amount)
+
+  const totals = {
+    amount: amountBn,
+    total: amountBn,
+    original_total: amountBn,
+    subtotal: amountBn,
+    tax_total: new BigNumber(taxTotal),
+    original_tax_total: new BigNumber(originalTaxTotal),
+  }
+
+  const isTaxInclusive = context.includeTax ?? shippingMethod.is_tax_inclusive
+
+  if (isTaxInclusive) {
+    const subtotal = amount.minus(taxTotal)
+    totals.subtotal = new BigNumber(subtotal)
+  } else {
+    const originalTotal = amount.plus(originalTaxTotal)
+    const total = amount.plus(taxTotal)
+    totals.original_total = new BigNumber(originalTotal)
+    totals.total = new BigNumber(total)
+  }
+
+  return totals
+}
+
+export function getLineItemTotals(
+  items: GetItemTotalInput[],
+  context: GetLineItemTotalsContext
+): { [itemId: string]: GetItemTotalOutput } {
+  const itemsTotals: { [itemId: string]: GetItemTotalOutput } = {}
+
+  for (const item of items) {
+    itemsTotals[item.id] = getTotalsForSingleLineItem(item, {
+      includeTax: context.includeTax,
+    })
+  }
+
+  return itemsTotals
+}
+
+function getTotalsForSingleLineItem(
+  item: GetItemTotalInput,
+  context: GetLineItemTotalsContext
+) {
+  const { unitPrice, taxTotal, originalTaxTotal } = toBigNumberJs(item, [
+    "unit_price",
+    "tax_total",
+    "original_tax_total",
+  ])
+
+  const subtotal = unitPrice.times(item.quantity)
+
+  const discountTotal = BigNumberJs(0)
+
+  const total = subtotal.minus(discountTotal)
+
+  const totals: GetItemTotalOutput = {
+    quantity: item.quantity,
+    unit_price: item.unit_price,
+
+    subtotal: new BigNumber(subtotal),
+    total: new BigNumber(total),
+    original_total: new BigNumber(subtotal),
+    discount_total: new BigNumber(discountTotal),
+    tax_total: new BigNumber(taxTotal),
+    original_tax_total: new BigNumber(originalTaxTotal),
+  }
+
+  const isTaxInclusive = context.includeTax ?? item.is_tax_inclusive
+
+  if (isTaxInclusive) {
+    const subtotal = unitPrice.times(totals.quantity).minus(originalTaxTotal)
+
+    const subtotalBn = new BigNumber(subtotal)
+    totals.subtotal = subtotalBn
+    totals.total = subtotalBn
+    totals.original_total = subtotalBn
+  } else {
+    const newTotal = total.plus(taxTotal)
+    const originalTotal = subtotal.plus(originalTaxTotal)
+    totals.total = new BigNumber(newTotal)
+    totals.original_total = new BigNumber(originalTotal)
+  }
+
+  return totals
+}
+
+export function decorateCartTotals(
+  {
+    shippingMethods = [],
+    items = [],
+  }: {
+    items: GetItemTotalInput[]
+    shippingMethods: GetShippingMethodTotalInput[]
+  },
+  totalsConfig: { includeTaxes?: boolean } = {}
+): CartDTO {
+  let cart: any = {}
+
+  const includeTax = totalsConfig?.includeTaxes
+
+  const itemsTotals = getLineItemTotals(items, {
+    includeTax,
+  })
+
+  const shippingMethodsTotals = getShippingMethodTotals(shippingMethods, {
+    includeTax,
+  })
+
+  const subtotal = BigNumberJs(0)
+  const discountTotal = BigNumberJs(0)
+  const itemTaxTotal = BigNumberJs(0)
+  const shippingTotal = BigNumberJs(0)
+  const shippingTaxTotal = BigNumberJs(0)
+
+  cart.items = items.map((item) => {
+    const itemTotals = Object.assign(item, itemsTotals[item.id] ?? {})
+
+    const subtotal = BigNumberJs(itemTotals.subtotal.raw!.value)
+    const discountTotal = BigNumberJs(itemTotals.discount_total.raw!.value)
+    const itemTaxTotal = BigNumberJs(itemTotals.tax_total.raw!.value)
+
+    subtotal.plus(subtotal)
+    discountTotal.plus(discountTotal)
+    itemTaxTotal.plus(itemTaxTotal)
+
+    return itemTotals
+  })
+
+  cart.shipping_methods = shippingMethods.map((shippingMethod) => {
+    const methodTotals = Object.assign(
+      shippingMethod,
+      shippingMethodsTotals[shippingMethod.id] ?? {}
+    )
+
+    const total = BigNumberJs(methodTotals.total.raw!.value)
+    const methodTaxTotal = BigNumberJs(methodTotals.tax_total.raw!.value)
+
+    shippingTotal.plus(total)
+    shippingTaxTotal.plus(methodTaxTotal)
+
+    return methodTotals
+  })
+
+  const taxTotal = itemTaxTotal.plus(shippingTaxTotal)
+
+  // TODO: Discount + Gift Card calculations
+
+  // TODO: subtract (cart.gift_card_total + cart.discount_total + cart.gift_card_tax_total)
+  const total = subtotal.plus(shippingTotal).plus(shippingTotal).plus(taxTotal)
+
+  cart.total = new BigNumber(total)
+  cart.subtotal = new BigNumber(subtotal)
+  cart.discount_total = new BigNumber(discountTotal)
+  cart.item_tax_total = new BigNumber(itemTaxTotal)
+  cart.shipping_total = new BigNumber(shippingTotal)
+  cart.shipping_tax_total = new BigNumber(shippingTaxTotal)
+  cart.tax_total = new BigNumber(taxTotal)
+
+  // cart.discount_total = Math.round(cart.discount_total)
+  // cart.gift_card_total = giftCardTotal.total || 0
+  // cart.gift_card_tax_total = giftCardTotal.tax_total || 0
+
+  return cart as CartDTO
+}
diff --git a/packages/utils/src/totals/to-big-number-js.ts b/packages/utils/src/totals/to-big-number-js.ts
new file mode 100644
index 0000000000000..15c2721383e2f
--- /dev/null
+++ b/packages/utils/src/totals/to-big-number-js.ts
@@ -0,0 +1,31 @@
+import { BigNumberRawPriceInput } from "@medusajs/types"
+import { BigNumber as BigNumberJs } from "bignumber.js"
+import { isDefined, toCamelCase } from "../common"
+import { BigNumber } from "./big-number"
+
+type InputEntity<T, V extends string> = { [key in V]?: InputEntityField }
+type InputEntityField = number | string | BigNumber
+
+type Camelize<V extends string> = V extends `${infer A}_${infer B}`
+  ? `${A}${Camelize<Capitalize<B>>}`
+  : V
+
+type Output<V extends string> = { [key in Camelize<V>]: BigNumberJs }
+
+export function toBigNumberJs<T, V extends string>(
+  entity: InputEntity<T, V>,
+  fields: V[]
+): Output<V> {
+  return fields.reduce((acc, field: string) => {
+    const camelCased = toCamelCase(field)
+    let val: BigNumberRawPriceInput = 0
+
+    if (isDefined(entity[field])) {
+      const entityField = entity[field]
+      val = (entityField?.raw?.value ?? entityField) as number | string
+    }
+
+    acc[camelCased] = new BigNumberJs(val)
+    return acc
+  }, {} as Output<V>)
+}
diff --git a/yarn.lock b/yarn.lock
index 2203412df7888..698f1efd27f3f 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -8707,6 +8707,7 @@ __metadata:
   resolution: "@medusajs/types@workspace:packages/types"
   dependencies:
     awilix: ^8.0.0
+    bignumber.js: ^9.1.2
     cross-env: ^5.2.1
     ioredis: ^5.2.5
     rimraf: ^5.0.1
@@ -8842,6 +8843,7 @@ __metadata:
     "@mikro-orm/postgresql": 5.9.7
     "@types/express": ^4.17.17
     awilix: ^8.0.1
+    bignumber.js: ^9.1.2
     cross-env: ^5.2.1
     express: ^4.18.2
     jest: ^29.6.3
@@ -21419,6 +21421,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"bignumber.js@npm:^9.1.2":
+  version: 9.1.2
+  resolution: "bignumber.js@npm:9.1.2"
+  checksum: e17786545433f3110b868725c449fa9625366a6e675cd70eb39b60938d6adbd0158cb4b3ad4f306ce817165d37e63f4aa3098ba4110db1d9a3b9f66abfbaf10d
+  languageName: node
+  linkType: hard
+
 "binary-extensions@npm:^1.0.0":
   version: 1.13.1
   resolution: "binary-extensions@npm:1.13.1"