A point of sale terminal

A POS terminal for a retail environment comprises a data acquisition device for generating event data from a user scan of a product along a scanning path of the POS terminal. A processing unit 214 receives at least a portion of event data from the data acquisition device and processes the event data according to a set of pre-defined rules to determine a control parameter for the POS terminal. A user alert is generated based on the control parameter and the alert is communicated to the user 212. The data acquisition device comprises a Universal Product Code (UPC) scanner; a plurality of illumination units 202, 204, 206 208 arranged along the scanning path for illuminating the product and a plurality of sensors 210, 216 for sensing event data including a shape, size and volume of the product and a parameter relating to the user as the product is scanned along the scanning path. In some embodiments only the volume of the product may be determined. The alerts can be scanning instructions used to improve the scanning efficiency of customer using a self-service checkout by providing an active guidance system. The volume, shape and size of products can be compared to predefined parameters.