A few days ago, my kids rediscovered the Melissa & Doug grocery cart one of the grandparents got our son for his second birthday. So the grocery cart has been moved from the basement to the living room. The other morning, A and M were fighting over the grocery cart and so I ran downstairs to get our play cash register, which I bought at the ARC for $1.50.
I set up a play Target store just by asking the kids what they wanted to buy at Target and they started putting toys in the grocery cart. Then our living became a Target check out lane. A and M helped put the toys on our window seat (the conveyor belt for the check out lane) and then I rang the toys through. A paid for his toys with play money he had fun putting in his tractor wallet. Maggie got to play with the zipper on one of my old purses. It was simple, fun and we already had what we needed. I think the skills we hit in this imaginative play were early math skills, vocabulary, narrative skills, gross motor (pushing the cart around), fine motor skills (zippers on purses & wallets) and social skills (working together to play and take turns). Plus, we had a lot of fun.
If you don't have the cash register or grocery cart, you can make your own cardboard box cash register. There are some great ideas already online that you can mimic. You can use a basket to carry instead of a cart to push. Here is also a link to free play money you can print, or you can cut out your own from green construction paper.