Data processing hardware, namely, card readers, cash acceptors, printers, monitors, interrogators, and input pads, and computer programs for the operation and processing of retail fueling units permitting payments via credit card authorizations, debit sales, cash acceptance and charge backs, smart cards and global computer network payments at gasoline dispensers and payment terminals, with such payments and merchandising options being linked via a server and communications network connecting site operations, namely, point-of-sale systems comprised of an interactive terminal with input keypad and monitor that determines goods and services purchased and handles payment acceptance and processing, back-office computer systems comprised of a microprocessor, keyboard and monitor interfaced with one or more point-of-sale systems, credit, debit, and smart card processing, underground fuel storage and monitoring, video security systems comprised of a camera, memory device and microphone and inventory