In countries where getting change from large bills is problematic, I hide my small bills that I do have and try every place I go to pay with the largest bill possible. Somehow they will usually find change though it may take a minute. I'll usually insist it's all I have because it's what the ATM gives out.

I have learned that you really have to hide the small ones though, if they get the slightest glimpse of them in your wallet they are quick to point out that you have one, lol.