[ic] 4.9.3 SalesTax calculation error

[Salvador Caballe]

There are an error in [salestax] calculation with discount  products, the 
tax is calculated with the regular price, instead subtotal

105.26 less 5% discount = 100 + 16%  (16.00) = 116.00

but the interchange calculation is:

105.26 less 5% discount = 100 + 16% (16.84) = 116.84

Salestax was 16.84  instead the correct valor 16.00

Version 4.9.3 
Tax configuration:
Tax type :VAT, based on country and tax category

best regards
Salvador Caballe