Abstract: A transaction processing system for retail stores includes a content management apparatus storing content files and a transaction processing apparatus. The transaction processing apparatus is configured to register a commodity in a transaction based on registration input received from a user terminal device and select a content file to be displayed on the user terminal from the content files stored on the content management apparatus. The content file is selected based on a user attribute associated with a user of the user terminal device or a commodity registered in the transaction. When a length of time since a registration input was last received without another registration input or user instruction being received exceeds a timeout period, the transaction processing apparatus causes the user terminal device to display information corresponding to the selected content file.