When you say "they" I could tell you exactly what format we stored card balances in, including the implied point position for different currencies (not the same for GBP and (say) JPY) and none of it involved DECIMAL!

> They use integers to store cents or fraction of cents or DECIMAL as alternative if not using integers

Seemed rather clear, what's difference with what you say ?

I referred to 'they' for my clients and start-up. You seemed to be making claims about those particular implementions, which seemed a bit odd.