Hello community!

I am an tecnician from austria and i work on an shop with Virtue Mart and VM Invoice.

First of all:
There are articles with 10% tax (books)
And products with 20% tax (the rest )

And there are coupons ( they are to see like money )
now when i look at the bill the component take the price and generate the tax sum.
then he subtract the discount from the coupons.
but in austria this way is wrong!
the end price is correct but the sales tax is wrong for austria!

Here is a example to show you:
 
1 Price 120 - no discount
-> tax 20 , - (with 20 % VAT)
 
2 Price 120 , - 50 % discount
-> tax 20 , - (with 20 % VAT) as it is calculated now
-> tax 10 , - (with 20 % VAT) would be correct, because the sale price is only 60, -

Our way must be that the component take the price of the product and subtract the discount.
Then it should take the result and generate the sales tax out of this.

please help me ;)

thanks!

greetings,
christian