The grocery store is a place of necessity, compared to the department store of diversity and choices. To dream of being in a grocery store may be to dream of acquiring sufficiency for one's needs. What is important is to look at whether or not the grocery is a good option for acquiring what is needed.
Does the grocery store fit your needs, or do you really need auto parts or some non-food item? This may indicate that you are looking in the wrong place for answers in your waking life.
Do your fellow shoppers seem at ease or harried, and is there a sense that there "isn't enough to go around?" This may indicate anxiety over finding a mate, locating the right job, or some other limited commodity in the waking life.