Purchase Rebate Threshold

Hi All,

Purchase Rebate is based on Quantity and Percentage level

Rebate Quantity   Rebate %

100                        10

200                         20

Purchase Order is raised for 8 Qty ( Amount is $40). Now when  R43400 is ran, Debit and Credit entries are created for $40, Which means Rebate Amount to be collected from Vendor is $40(correct if my understanding is wrong), if Correct, the above calculation is wrong, because Rebate Quantity is set for 100 Quantity ( Rebate Amount should be calculated only when Purchase Order is created for more than 100 Quantities)

Kindly Clarify.