Meanwhile, the cashier area will be normal for the customer to enter the silver tipped. Because of her presence might create embarrassment to an employee or potential employee receiving tips, no rules.
The cashier will usually have a jar for customers to put any money down. The tipping presence could create embarrassment to the employee. Or some may have rules that employees not get a tip.
Normally the cashier is for customers to put the tip jar. Because tipping before may create trouble for its employees. Or maybe there rules from the tip.