WASHINGTON (WUSA9/CNN) -- The sales clerk asks you for your zip code after swiping your credit card, but you may want to think twice about giving it to them.
Consumer Jo Ann Davis takes her privacy very seriously.
So when she tried to return an item at an Ulta beauty store and was asked for her zip code, she stood her ground.
"When I refused to give my zip code they called the manager. She wanted it - and then said that she couldn't go forward with providing me with a refund or a store credit or whatever," Davis says.
Davis says it led to an ugly confrontation in the store. You have probably been asked for your zip code at a retail store and maybe wondered why they want it.
"Stores can take this information to a data-broker and ask them to match up the name with the zip-code in order to get the person's home address. And they can get other information too. They might be able to get an e-mail address or a phone number as well," says Chris Hoofnagle with UC Berkeley Law School.
Retailers can take that information and target you for your marketing campaigns. They can share information about you with other retailers. They can even learn more about your income or whether you have gone through bankruptcy.
Davis is watching her own back: "Whenever there are those reward programs, I do give a fake birthday and you know, in this case I could've given them a fake zip-code. But why should I have to do that?"
Ulta has offered to make it up to Davis, but they didn't comment on the practice of asking for zip codes.
In some cases, retailers are asking for zip codes simply to understand where their customers are coming from so they can make decisions about how to use their advertising resources.