Personally, as someone who used to work in the food industry, I always found myself trading out 20s for 50s and 100s. It's easier to count, keep track of, smaller stacks, and just... better. That being said, I've paid people with straight 20s before and vice-versa or even smaller bills. Depends on what it's for and how often it happens. If someone is bringing me a few hundred 1s at a time or trying to pay me in 5s everytime then I'd tell them to get some bigger bills (just because I make it a point to do the same) but still take it. It's money, and money is money is money. Some is just better.