Retail items movable from an inventory location at a retail venue through a portal to a retail exit are automatically tracked. The items are individually associated with radio frequency identification (RFID) tags. An RFID tag reader has an array of antennas for generating a multitude of scan beams at an adjustable scan rate. A first set of the beams covers the inventory location, and a second set of the beams covers the portal to determine an exit characteristic of the items that have exited the retail venue. A point-of-sale workstation at the retail venue is operative, independently of the tag reader, for determining a sold characteristic of the items that have been sold. A controller dynamically adjusts the scan rate of the first and second sets of scan beams to an optimal scan rate as a function of the determined exit and sold characteristics.