Is there a way to calculate a percent discount on a purchase order?

We're on PeopleTools 8.61 and FSCM PUM 53.

We enter requisitions in eProcurement that contain catalog items. These items are on procurement contracts. We use PO autosourcing to source requisitions to purchase orders.

We have a contract where the vendor will give us a 5% discount on purchase orders over $300. While we can apply the discount to the voucher during payment, this would not be reflected on the purchase order.

Is there a way to have the system calculate the discount based on the PO total amount, and then apply it to the purchase order total amount?

I see there is a price adjustment template link on procurement contracts. Can I use that to calculate the percent discount? Is there documentation on how it works, other than PeopleBooks?