All business entities that use cash forms of receiving and/or giving money or other securities are obliged to conduct cash operations. Computer-supported cashier operations are required to be run by all business entities that have organized retail sales as part of their operations due to the obligation to fiscalize accounts. However, today there is almost no business entity in the Republic of Croatia that performs cashier operations manually. Users have at their disposal large and expensive software solutions that small businesses, especially startups, cannot afford. For this reason, a study was conducted with the aim of defining a relational database model for the cashier operations of small entrepreneurs who do not have generous funds to purchase ready-made software solutions. The focus of research conducted in practice is the extraction of essential individuals (entities) and their attributes using the method of abstraction. The relational model of the database for cashier operations is defined mainly by the aggregation method, which can fully meet the needs of cash registers for small businesses with its coverage of entities and associated attributes and its structure. MySQL was selected as the relational database management system on which the testing was performed, and the "MySQL Workbench 8.0" program package was used as a tool for creating the database and testing it. An experiment was conducted by simulating cashier operations by entering and updating data in the modeled and formed database, which demonstrated the usability of the solution. In addition, a descriptive model of the Web software application for cashier operations was created. Accordingly, the results of the conducted research indicate that it is possible to define a database model that would enable small business entities to easily manage cashier operations with or without the use of a ready-made software application.