Discounts percentage can be applied individually against the material item when creating a Quote/Sales.
Or in bulk via price levels:
Set up price levels
Bulk update price levels
Have a look at similar frequently asked questions or visit our FAQs page for more information
How do Pricing Levels work with different currencies in TidyStock?
Does voiding a sale in TdyStock also cancel it in Xero
How do I give a quote?
Can I bulk update supplier prices in TidyStock?
Can a team member change the status of a purchase order once it has been approved, rather than having a manger do it?