We have the £10 one from Wilkinsons which has a moving conveyor belt, beeping scanner, microphone, drawer bell etc. DS loves it. I've just bought him a wooden shop/cafe for xmas so I was planning to replace it with a wooden one but they all seem so boring in comparison!
https://www.wilko.com/make-believe/wilko-play-cash-register-playset-3+-years/invt/0320856