There are two types of discounts: general and product.
1. Whole purchase: It works in the total.
To add this type of discount the vouches must be created.
In the total column you can click on discounts, and a list will be shown. I this list you can select the discount and add it
2. By product: they work in the product line.
To apply this type of discount you can clic on the "disc." column and write the discount. You can add discounts by percentaje or amount.