I say sure, hand them the receipt (most of the time unless if there’s something I might need to return) and keep walking.

All they asked was to see my receipt. They can look at it all they want.

I do this as well. One day I was in a hurry on a lunch break and I was getting batteries and a sandwich, literally two items in a single bag. The person stepped in front of me and started to ask to see my receipt and I just snapped out “no thank you” but when they just stepped aside I realized there was no reason to ever let them and I havent since.