Perhaps there is a market for some kind of service that allows you to make small 5 or 10 cent charges. All of these charges are grouped together and you make a payment at the end of the month in one go so the the fees are reduced.
Or it could work the other way round, you top up your 'account' with amounts from, let's say, $10 upwards.
This could be monetized by charging businesses to integrate your service into their products.