At the Supermarket by Anne Rockwell

From chapters.ca:
On a special trip to the supermarket, a young boy helps his mom buy what they need. There are meats, fruits, and vegetables to put in the shopping cart; soap and toilet paper, too. But the most important ingredients are those needed to bake a birthday cake. Children love to help out at the grocery store. In her signature style, Anne Rockwell conveys the thrill of a trip to the supermarket from a young child's point- of- view.