If you want to push your app's wallet (for cash-flow, loyalty, interest margin), you could offer additional reward bonuses for larger reloads.

i.e. a $10 reload gets no bonus, but a $30+ reload gets an extra dollar in rewards.

Presumably you've already seen the CUPS coffee app, but check it out if you haven't. They're dead as a company now from what I can tell, but they had a very streamlined experience. They even tried a fixed price model where each vendor would receive a fixed payment for each cup users redeemed and users would subscribe to a plan with a certain number of cups a month.