Here's my understanding of it:
The repayment bonus for consolidated loans is .75% and the bonus for med school stafford loans is 1.3%. Basically, they will deduct this rate from whatever your current interest rate is. So if you pay 3.5% in interest, then with THE, you're really only paying 3.5-1.3 or 2.2%, because THE will add your saving to your account every month. So if your 1.3% credit comes out to be like $10, THE will give you a $10 credit every month.
I'm sure someone will correct me if I'm wrong 😛