I always carry some coins (dollars, quarters, dimes, and nickels), since I have been dropped off at airports with no prior notice (while on a recon mission) to lighten the helo for 1 more body when the aircraft was diverted for SAR (when in doubt, dump the QM, and refuel). These coins allowed me to phone for a ride, get food and drink from vending machines, etc.

Being coins, I don't tend to spend them (too lazy to dig them out), unless I have a legitimate need for them. I add to them everytime I get some of the new dollars, quarters, and nickels. That's usually twice a month during each crew change.

It works for me.