Doesn't help much when the ^&%#$&^%# cashier carefully places a stack of coins in the middle of a stack of bills, picks up the stack of bills by the ends, and hands the unstable mess to the customer.
Most such cashiers, FWIW, IMO, seem not to have been born in these United States, nor do they appear as though English were their native language. They also do not appear as though Spanish were their native language.
In that case I just say “could you hand me the coins and the bills serperatly?”
No cashier yet has failed to do so, when aske polietly (some look at me funny, but who cares).