Excuse me, where is the laundry detergent?

Excuse me, how much does that cost?

It costs 99 cents.

That'll be ten euros.

Where's the checkout, please?

Are you paying cash? (formal)

I would like to pay with my credit card.

We do not accept credit cards.
That's a special offer.
etwas kaufen
kauft, kaufte, hat gekauft
to buy

I'm buying soap.

That's too expensive.

Would you like a bag? (formal)

Here you go.

Thank you very much.