Toss the receipts unless buyer asks. I found in selling a car if they ask for receipts once they see the pile(I put sticky's in major maintenances) they don't ask any further on maintenance or for them either.
In a moment of brilliance... I left the insurance card and registration papers in the glovebox. Go figure. I suspect that is ok though, I have the plate, will cancel the ins today. But a moment of pure smarts on my part.