A tracking-based point-of-sales (POS) system includes a first sensing device, a second sensing device, and a processing device. The processing device is configured to perform location tracking with respect to the one or more customers around the product display section based on location information, perform a first operation to determine a purchasing customer who has performed a product displacement activity based on a result of the location tracking, and perform a product registration. The processing device is configured to perform a second operation to determine a product-returning customer who has performed a product placement activity based on a result of the location tracking, and perform a product deregistration. The processing device is configured to, upon the product deregistration causing an anomalous number of product in a purchase list of the product-returning customer, perform an anomaly operation.