Great work!
I tried to use your contribution for a payment type percentage discount. (like moneyorder:0:%-2,cod:0:%-2, etc.) The module has no problem with the "negative percentage", but the VAT/BTW does not get changed. It keeps using the product subtotal.
An example:
Subtotal: €100,-
Payment discount: -€2,-
BTW/VAT: €19,-
Shipping: €6,25
Total: € 123,25
It ought to be:
Subtotal: €100,-
Payment discount: -€2,-
BTW/VAT: €18,62
Shipping: €6,25
Total: € 122,87
Could you help me figuring this out?
Thanks!