small amount recurring billing

I want a website is to support micro charity's by giving them easy access to the funding options that the larger charity's use. In this case less then $1 per day donations, using an ipad and credit card. I need to know what %fee the processing will take (the lower the better). I want the charity's to be able to create an account and get paid with as little effort as possible. I need a website which can collect and processing small amounts. So that we can ask the customer for recurring amount to be taken out of their account weekly after the sale has been made. The front end should be wordpress but this is optional. The web site will have: an affiliate scheme a developer with proven SEO skill an ipad, iphone, android api FB, twitter, etc like/share buttons