Age you need to be to work at a grocery store such as shop rite&giant to put away cans and clean?

Probably 15 or 16.

you need to be atleast 15.

It depends on the state (country), store, and local labor laws. I live near a Publix (Regular gorcery store here in the south if you dont know) and they start hiring at 14 years old. At 14, you can bag, unload floral boxes and sort flowers, and do minimum bakery stuff, and do a little bit of can organzing and stuff like you said, but mostly bagging. As that is pretty awesomly fantabulous for us 14 year olds in SC, the waiting list is SOOOOO long (i was in the list with 4000 people so I kinda gave up) so they pick the older, more expierienced people to do the job rather than the desperate 14 year olds. South Carolina is (I believe) the state with the most low labor age jobs. You cant get a job less than 14.
I'll prob just work at the BK when Im 15. :)
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imawalrus