Access the POS back office here.

Go to DISCOUNTS and then Predefined discounts.

Tap ADD NEW and add the name, description, and validity (how long it is good for).

Tap DISCOUNT under Predefined discounts.

Select a DISCOUNT TYPE from the available choices.

Add the category of products that you want the discount to apply to.

If you only want certain products discounted, tap the + symbol next to the category name. (Like in the image below.)
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5. Tap UPDATE to save the changes.
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