Tier Pricing help

Hi all,

Hoping someone can assist with the below, I have tried a couple of ways to do this but can't seem to get the result I am after.

What I am trying to do is count the number of transactions between each band and charge at the rate according to the band.

For example, a customer has total of 250 transactions so 200 @ 0.04, plus 50 @0.02 = $9 Total due by customer

The bands I am after are the below:

Band Start Band End Fee Per transaction
0 200 0.4
201 300 0.02
301+ 0.01

Thanks for any assistance you can provide in advance...