I suppose that would teach the kid a lesson.
The banks still pay a very low interest rate, but 6-month T-Bills are up to 2% (annual).
You can buy them through the Internet, and hold them in a US Treasury e-account.
Don’t forget to teach little Johnny about inflation (his $50 worth < $50 in a year w/ any inflation above said 0.10%), or the taxation his ‘windfall’ of $.05...if the bank doesn’t charge a fee for the account to begin.
There’s a reason economics, and Civics, isn’t taught anymore...