What determines the amount of money paid back at Congress?

[Crabtree Farm]

I was curious what determines the amount of money paid back at Congress in the Stakes classes and Incentive classes? Or is there a set amount for each placing?

 

[muffntuf]

Entries is the first that comes to mind. But Joe in the office is the one you want to talk about to for the incentive and stakes classes. He's been doing it for years and has it pretty well down pat.