How to give a discount ?
Users can give discounts to customers in 2 ways - on the billing screen or to avail discount menu modifier
1) Discount on the billing screen
Discount (%) - Discount in percentage on the bill
Fixed Discount - Fixed discount on the bill

Billing Screen
2) Discount menu modifier
A discount menu modifier can be added while creating or editing the menu from the admin panel

Discount menu modifier
Admin can allow certain permission and authentication from discount from admin panel.
Please click here to create a discount in the menu modifier