I'm about 95% of the way done writing a WPF/C# point of sale application to interface with nopCommerce but have a couple of questions that I'm hung up on - figured someone may have some easy answers.
OrderProductVariant
DiscountAmountExclTax - I assume that this is the amount that was discounted off of the order?
DiscountAmountInclTax - Since a discount is applied before tax, how can this possibly be calculated? We're not discounting the tax, we're discounting the item price. I can calculate how much tax *would* have been charged on the discount amount, but why? It seems to add needless complexity for data that I can't see a need for.
Order
If I apply a discount to the entire order, then that affects the tax collected on any given item. With that in mind - how should a discount be applied to the order? Do people generally apply it evenly (5 items would get 20% of the discount amount each)? What if the discount amount per item is more than the item price itself?
The questions actually aren't even specific to the PoS application, they're a general design question for the tax module experts here. The store I'm writing this for is located in New York which has a lot of tax rules - I'd like to try and get this correct from the get-go.