Custom Rounding

[lukasNo1]

Hello

In Switzerland we round both cash and online payments to 5 cents. But this is currently not possible with craft commerce.
it is technically possible to pay online in 1 cent increments but most companies use the 5 cent rounding everywhere.

There was a related request opened to this some time ago (Link), but I have not found a feature request for this so far.

The following would be the rule:

9.99 must be rounded to 10.00
9.98 must be rounded to 10.00
9.97 must be rounded to 9.95
9.96 must be rounded to 9.95
9.95 must stay the same
9.94 must be rounded to 9.95
9.93 must be rounded to 9.95
9.92 must be rounded to 9.90
9.91 must be rounded to 9.90

As mentioned in the article above we only really need to have this rounding for taxes and discounts as the product prices are already entered manually with the correct rounding.

Taxes
Taxes are a problem for us since we use a tax rate of 7.7% which can lead to "odd" tax amounts (and this leads to "odd" total amounts).

Discounts
Discounts can also be a problem since they also sometimes lead to "odd" numbers (i.e. a 10% coupon on 14.85 is giving a discount result of -1.49 instead of -1.50).

Is there any way you could implement this?