Which action is necessary when opening a register?

When opening a register, it is essential to count cash and prepare for transactions. This step is crucial because it ensures that there is an accurate amount of starting cash for the business transactions of the day. This process involves verifying the cash drawer against the expected amount, which helps to prevent errors in financial reporting and ensures that there is sufficient change for customers making purchases. Having the right amount of cash available contributes to efficient customer service and smooth transaction processing throughout the day.

The other actions listed, while important for various aspects of retail operations, do not directly pertain to the initial action needed at the start of a cash register's operational day. For instance, printing sales reports typically occurs at the end of a shift or day, stocking merchandise is related to inventory management, and clearing previous day's transactions pertains to record-keeping that happens at different times, not necessarily when opening a register.