Collecting money is often reserved to the Boss when it is a small enough business. When there is a secretary or cashier or accountant who collects money, this is where it gets tricky.
The person who collects the money and gives the receipt may, when a business is busy and booming, be able to hide that amount, especially when it is the last payment.
The money is pocketed, and the remainder goes to the bank, and it may not be quickly discovered.
With the Internet and online banking, it might be useful to consider not taking money at the office.
Another problem with money is the deposit.
There are a long list of cases in which the person who carries the money is ‘robbed’. In these cases, the person who is ‘robbed’ has set up the robbery.
Not having protocols here is vital. Money collected is to be deposited at different times, different places, different methods, etc. so that no one knows if a deposit is going in and when.