* This module will try to get original unit price from the sale order and not
  use the Current unit price of the product.
  (The price at which you pledged to sell the product).
  Some VAT troubles will occure if a product is set with VAT marked as
  'VAT included' and if in the sale order line, there are some VAT marked as
  'VAT excluded' for exemple.

**The VAT settings should be consistent.**