Discount on Sale

You can set a separate discount for a product after adding the product to the shopping cart.

After adding the product to the shopping cart, tap the product briefly and select Discount.
Then choose the desired discount:
Sales line % discount
Sales line € discount
Product price € discount
No discount

After tapping one of the three discount options, this window provides a field to enter the discount amount, and by tapping OK the discount is reflected in the price.