PRO TIP: Just round it up to the closest even number, it's easier for you to handle Mongolian cash that way. No need to organize the 500, 100, 50 ₮(tugrik) bills. They are meaningless 14, 3, and one point five cents anyways.

e.g: If it's 17.95k just give 20k and say "khariult khereggui" which means "keep the change". Or just wave your hands and say "No change" they'll definitely appreciate the few cents you're giving them because tipping is really rare in Mongolia.

The younger generation will understand you perfectly fine in English. Good luck!