That's a price, not a balance or amount transferred. Any sub-cent stuff is handled internally by the gas station, then rounded to the nearest cent and transferred to external banking APIs. The gas station is free to use whatever representation it wants for the price and quantity, so long as it rounds to the nearest cent before pushing to the API.
Sure, I probably should have specified that I meant in general when handling money, not necessarily specifically for handling payment API calls. I've worked on a system that kept track of arbitrary precision separately while using integers to store the values. Worked reasonably well, all things considered.
But you're right, we wouldn't have expected to be able to call something like stripe with that same arbitrary precision. It was all internal pricing.
