You could try Amazon FPS < http://www.amazon.com/Flexible-Payments-Service-AWS/b?ie=UTF... >. I'm not sure, but I think you might even be able to use them to bill less than 1 cent.
"Micro-Payments Support: With Amazon FPS you can track and aggregate micro-payments (e.g. payments less than $0.50 or even $0.01) into a single payment transaction"