In our case, the percentage would be more than to just cover the merchant fees. It would also be to make a little bit of profit, yet we didn't want to overcharge those that donated a lot. 10% on a $50 donation is only $5, which sounds fine. But to charge 10% on a $1,000 donation would be $100 which would be way too much. And unfortunately, a flat rate fee won't work, because if you get a very large donation, it may not cover your merchant fees. I would think this would also come in handy for those using this field for shipping charges, as well. If anyone else would like this feature, let us know. Thanks, Janice