This option is only available if you have the Retail feature included in your Jim2 key. If not, whilst you can make entries here, they will be ignored.
On the ribbon, go to Tools > Setups > Banking > Tills.
As part of the setup to operate Retail, you will first need to name (add tills) the Tills that you use (code and description), then assign each retail workstation one of these Tills.
You can have more than one workstation using the same physical Till. Allocation of Tills is done via Options > Retail.
You should nominate the amount of the float for each till, which will then reflect in the cash calculation in Till Reconciliations.