Do you have to rent a cart and bring your own bags for the stuff you buy? That is how it is run here in da US..
'Rent a cart'???
I think he means one of these, it'll be €1.
Also we have none of this standing about and taking your time, what happens, you pay for the groceries and then get them all in the bags as fast as possible, anyone taking their time, they'll at the best get some very severe looks from everyone and at the worst they'll be verbally told to stop taking their time.
You should aim to have everything bagged in under 4 minutes and then out of the store.