calculator script?

Where can I find a fee calculator like this...?
Season's Greetings,

I need to add a calculator to my service web site that will caculate a customer's service fee based on the denomination of money order they wish to send and then let them place their purchase. It should work exactly like Bidpay's fee calculator, if you can remember.

A similiar example would be Western Union's fee calculator located here:

http://www.auctionpayments.com/

It's on the right, in the yellow box that says "Price It!".

Anyone know where I can find my own similiar fee calculator? I've looked everywhere. And lastly, how do I integrate it into my payment processing process?

Cheers and Happy Holidays!

Just write a script to calculate it based off your fee schedule, and then pass that value to your payment process as you would any other charge from your site.

-Confluent