Role/User locked accounts/sales person name?

Role/User locked accounts/sales person name?

Scenario,
I have multiple cashiers, and in the end of the day I want to be able to calculate how much does each cashier have in their own specific own Petty Cash Account and they should be locked to that account only.

Is it possible to lock and assign specific accounts to role/user? 

For Example, James issues 7 cash invoices worth 1000 total, and Tom issues 10 cash invoices worth 2000 total, right now with Zoho all invoices go to "Petty Cash" I want that to be locked and make 2 accounts, lets say, "James - Petty Cash" and "Tom - Petty Cash" and they can't change/select that. So in the end of the day, I know which cashier has how much money.

If not the above,

Is it possible to assign "Sales Person" name to a specific user so when they issue the invoice, it's locked with their own name and they can't select some other sales person's name.

Even if it can't be done, is there any ways around it so in the end of the day I can calculate total cash based on each person's name. 

Any help or trick will be greatly appriciated because I want to buy Zoho, just waiting for this final answer.