Typically, ATMs (Automatic Teller Machines) do not receive or dispense coins, and they do not dispense smaller bills like 10s, 1’s, or 5’s, reasonably, due to limited space in the machines, though they do accept smaller bills in any denomination. There is a way that ATM machines can accept and dispense coins and smaller bills of all sorts…
Pneumatic tubes, or systems that propel solid, cylindrical objects through networks of tubes by vacuum could be connected to stacks of relevant coins and bills in stored cash reserves at each bank, and could be propelled through the relevant tubes when requested or deposited by bankers.
I discussed in a previous post the need to incorporate all external tellers into bank and other synonymous buildings for the protection of armored guards who deliver cash to ATMs, etc. This would facilitate the coin dispensing process.
Exclusively digital currency would be the very best form of universal monetary exchange; until this is realized and/or implemented, traditional currency in all denominations should be conveniently accepted and dispensable from any automatic teller.