Multiple Variables In A Commission Structure

I'm trying to create a worksheet to calculate ourcommsiion structure, but can't figure out a way to attack it. We have manyvariables (5) in our commission structure based on each order.

Here's how I set it up so far:

(In Cloumns)
A= Order Amount
B= "Y" is A-15%; "N"=A
C= "Y" is B*20%; "N" is B*10%
D= "Y" is B+2%; "N" is B
E= "Y" is B+2%; "N" is B
F="Y" is B+1%; "N" is B
G= SUM(A:F)

For example, if the order is $1000, and I answer y,y,y,y,y=$212.5

How do I create the formulas so I can just put in the order amount and the
appropriate letter to get the correct commission structure?