KaHero POS allows you to add discounts to your items and sales.
Under "Listings", select "Discounts".

Click "Add a Discount".

Input your discount name, discount value, and whether the value is "By Percentage" or "By Whole Number".
A. By Percentage - a percentage of the transaction's or item's total amount will be deducted from the grand total.
B. By Whole Number - a specific number of the transaction's or item's total amount will be deducted from the grand total.

Click "Save" and you can now apply discounts to your sales.