Mine go in the ass-pocket until the stack is too big, then into a ziplock bag, then into a box.
I have a copy of every receipt I've gotten for the past 12 years in almost chronological order. 90% of them are probably faded. Looked at old ones < 30 times, maybe.
I might be some kind of hoarder. :\
I used to keep my receipts over the course of a whole year, then throw them away in January.
Trying to get into the habit of only keeping the ones for major purchases.