It's hard to believe there's a tipping question that hasn't already been bludgeoned to schist but I couldn't find this situation in searching.
I recently had a solo dinner at an ethnic restaurant which only had one other table occupied, by a couple. My tab came to just under $15. I put a 20 in the folder. The waiter did not ask if I wanted change. He took it, returned a little while later with the folder, then vanished. It contained the coins, and a $5 bill. Though service had been slow and inattentive, I was planning on leaving $3 but assumed the waiter would be bringing the change in singles. I only had two singles in my wallet. Adding that to the change brought the tip to $2.35, which was 15%, so that's what I left. Had the waiter reappeared, I'd have asked him to make change for the $5 but I have never before had a server who did not automatically break $5's or $10's in this type of situation.
Servers and other restaurant employees, what is the norm? Did I need to specify that I needed singles, or should he have foreseen that possibility and made change accordingly?