Australian $100 bills: It's quite easy to get these (make a withdrawal at the counter instead of using the ATM), but most people just don't bother because they've got debit/credit cards, and: AT Ms that used to dispense a wider variety of notes (and were more complex as a consequence) use $20/$50 bills because in multiples of 10, there are only two amounts you can't achieve with a combination of those bills - $10 and $30.