I created payment buttons, and tested them myself using Firefox (and I'm on a Mac)
While visiting a client I went to show them how the checkout would work for them and on the cart summary page, it would say "$175" for the service, but the subtotal was kicking another dollar on the price.
They are on an older system with some IE on it. Not sure that should have mattered though?
Also, had some others test out the payment page who had no issues either. I'm not sure what system they are running.
Going back and testing a payment myself, I have no issues.
Any ideas where this issue may have stemmed from?