I said, "I'll buy them." (I know I can hand them off to someone going that way eventually.)
"Seriously?" she said, and I nodded.
I offered her USD5 for her EUR5. She looked unhappy. "They're worth more than that."
I shrugged. "Yes, but you can spend five dollars here now."
She accepted my offer. Part of me thinks I should have offered her $6, which is what the EUR5 was worth at current rates, but I note that she wouldn't have been able to change the Euro coins at her bank -- they only want notes -- so I try not to feel bad about it. Besides, I have to hold onto the Euros until I can send them back to a place they're spendable when I run across someone going that way.