I remember one time when I was buying some stuff at a store and just when I was about to charge my credit card the machine (credit card machine or whatever it's called) wouldn't work. Since I didn't want to spend any cash I asked the girl at the counter if she could keep the merch for me and I'd come back later and pick it up (once the machine is hopefully back in order).

Is "keep" absolutely wrong there? I know that "hold" would be the usual word but I've also heard "keep" in situations like this one from native speakers. I know that "keep" usually means "to retain something permanently".

'Keep' is a natural word here. The context makes it ckear that it's only a temporary arrangement.

Thanks, Clive.