A feasible way to collect dollar payment?

I run https://extracttable.com for which I charge 0.0145$/credit. The motivation behind is making it easier to extract tabular data from images, AND not needing to pay for what you do not use.

I want my users to buy credits as little as possible AND service usage charged per transaction(1 transaction @ 0.0145$ != 14.5$ of 1000 transactions). Currently, I'm asking my users to buy a minimum of 100 credits (https://extracttable.com/#pricing) costs 1.45$ - after PG(PayPal) processing I receive a mere 62% of what user paid.

Do I have any recommendations from the community on improving the situation matching my with requirements.

TIA