It wrong-foots me as I try to figure out how to answer.
I reply 'No'. They think that means 'No I don't want help'.
I say 'Yes'. They think that means 'Yes I am ok with the packing'.
It should be: 'Can I help you with your packing?'
If I do want help, I end up saying 'oooh yeah. I'd love a bit of help...' to be really clear.
But is it an intentional ploy on the part of the checkout operator? Cos they all seem to do it.