A number of valid points made here and I offer one more for consideration. In addition to the larger denomination bills, 5, 10, & 20s that are routinely carried, carry at least 20 - $1 bills, reasonably new and clean. The rationale is simple, many vending machines take the 1's when they won't take quarters, (ie: rest areas, hospitals, hotel lobbies, etc). It might well be the difference between eating and going hungry. Additionally, it may prevent the carrier from being overcharged in a situation where the rule is cash only and little small currency is available to make change. If carried seperately from the other cash, it could be used as a diversion to get out of a bad scenario, mugging et al. YMMV.