Should custom discounts only be offered by you or your representative? Then restrict offering them. 

This is how it works ...

1. Log in as an admin.
2. Tap on [Menu] > [item list] > [Discounts].    
   
3. Tap on [] at the top, hide Custom Discount and tap on [SAVE].   
   
4. Done.    
   

All employees can now only apply the saved discounts and cannot provide a custom discount. This setting can be changed by users with admin privileges or a role with the "Manage Discounts" privilege.