I can tell you've been there...
Sure there are the nice ones who say "don't worry about it" and when you DO give them the change they say "Oh, thank you very much" and they smile at you, not expecting giving them back their 15pence change...
I swear to God next time when some bang out of order pax who thinks i'm gonna run away with their 50pence at 35.000feet up in the air, i'll just start crying " Oh no, how am i gonna pay may mortgage now, what am gonna give the kids to eat for dinner for the next 5 centuries if you're taking the 50 pence away from me???"
No matter where you are, up in the sky or on the ground, the rude ones will always remain rude. Unfortunately.
Such is life eh?
Take care. XX