Ive never counted it neither i find it uncomfortable, i have been short changed by £100 once, but its my fault for not checking, most do ask us to check it.
I always check in front of the new owners. Never had a problem after all there is nothing to be coy about they know how much the pup is and it is no different to buying anything else. There is nothing underhand in selling a puppy so why act furtivley when taking the money. Best to do it together so any shortfall/extra can be seen and sorted immedialtly. I would not expect Asda'a to accept an envelope furtivly slipped under the counter ;) Might be worth a try though LOL Aileen