One of the ways to practice your English in the USA is to go to a store. Someone will definitely come up to you and ask if you need any help. All you should do is start speaking, and the conversation will take off. Hopefully, you will find some of these expressions useful.

When you enter a grocery store, you will find a shopping basket or a cart. Then you start browsing and looking for the things from your shopping list. There are usually signs above every aisle so that you spend less time finding what you need (Fruit and Vegetables, Dairy products, Fresh Meat, Fish, etc.)

What you can say:

What time do you open?
What time do you close today/ tomorrow?

Do you have any organic crackers/ chocolate chip ice cream?
I'm looking for frozen pizza/ Italian pasta.
Could you tell me where the olive oil is?
Where can I find the washing detergent/ toothpaste?
I wonder if you could help me.

Do you have anything cheaper?
It's not what I'm looking for.
Do you have more items in stock?

I'd like to return this.
Could I speak to the manager?
I'll pay in cash.
I'll pay by credit/ debit card.
Can I have a receipt, please?
Can you gift wrap it for me?

What the salesperson might say:

We're open from 9am to 8pm, Monday to Friday.
We're open from 10am to 9pm, seven days a week.
We're open 24/7.
Are you finding everything OK?
I'm sorry, we're out of stock.
I'm sorry, that's the last one.
I'm sorry, that's all we have left.

When you are done shopping, you have to go to the cash register. If you have less than 10 items in your basket, you can use express checkout, which will save your time. You have to put your purchase on the moving belt and the checkout assistant will scan them for you with a barcode reader. Then they package your groceries, you pay for them, and you are all set.

The checkout assistant can ask you:

How are you going to pay?
Would you like a bag?
Would you like to donate money to...?

What you can read/ see:

Good value
Buy 1 get 1 free
Buy 1 get 1 half price
Reduced to clear
Half price