Yup. To be honest, I think packing on the shelf is much easier. You can happily pack at your own rate and sort yourself out without the pressure of knowing someone's in the queue behind you.
Does your one have a shelf in the window past the checkouts? I believe the idea is that you shove your stuff back in the trolley/basket and then actually pack over at the shelf. That's how (and others I see) do it. Much easier and keeps the queue flowing more quickly.