This question already has an answer here:
I often have small change leftover after visiting a country, usually much less than $1 equivalent.
Keeping it around is a hassle, especially if I'm unlikely to return to that country: I would have to sort it, remember where I put it, remember to look before I travel, etc... In my view this is far too much effort for the few cents I can potentially save in a jar somewhere.
What else can I do with this change?