It’s like the most persistent sales clerk you’ve ever encountered.

Major retailers are working with a new smartphone application that tracks and offers promotions to shoppers as they move from outside the store, to counters, to cash registers  even inside the dressing room (now that’s persistence).

The app, called Shopkick, will be available on Tuesday for the iPhone and in the fall for Android phones. And with five major companies supporting it  Macy’s, Best Buy, Sports Authority and American Eagle Outfitters, along with the Simon Property Group, the prominent mall operator  it is getting a big introduction.

Customers with the Shopkick app will get points (called kickbucks) for entering a store. Pick up a putter at Sports Authority, and points drop into the app. Stop in the dressing room at American Eagle, and more points arrive.

The points are redeemable for gift cards at the retailers, along with music downloads or credits toward Facebook games. It takes a lot of points, however, to earn even a $5 gift card, although the stores say they may adjust the point system to make points more valuable.