Just for marketing to see where their customers live. If most of the customers live in one zip code, they will open a store there knowing they already have customers there. You don t have to tell them, it just helps them out where they should have stores.
You don t have to tell them your zip code if you don t want to.They ask for this for marketing purposes and so that they can determine what geographic area most of their customers are coming from. They are just trying to determine where there target markets are.
Marketing purposes. This can help business determine how marketing is working in certain areas and where they need to increase it.