Having trouble calculating commission which commissions portions of a sale differently

[Marobeast678]

Hey,

Trying I am having trouble calculating commission which commissions portions of a sale differently. For example, if you have a sale that is 9000 USD. The first 3500 gives a commission of 4%, the 3500 after it gives a commission of 4.5%, and anything after that is commissioned 5%. Can anyone show me, while utilizing the vlookup function, how to do this? 

TIA

[#2]

@Marobeast678 

Create a small lookup list as in the screenshot:

Column I shows the increment from each tier to the next.

With a sales amount in A2, the commission is

=SUMPRODUCT((A2>$G$2:$G$4)*(A2-$G$2:$G$4),$I$2:$I$4)

[#3]

@Hans Vogelaar Thanks for the help man, I tried it, it worked very nicely.