€10 million: the amount of unclaimed change held by Dublin Bus. It’s collected some €13.3 million since 2001, with “about a quarter” reclaimed each year.
I’ve commented about this before – and particularly the fact that you must have the original ticket attached to the change receipt for it to be valid for a refund (though you might get away without it if you ask nicely).
There are a number of comments in response to the Present Tense post about giving the tickets to charity. In the end, what I did with mine was give them to the Dublin SPCA. Just post them to them – saves you the hassle of heading off O’Connell Street in the middle of the day.