Select on Settings > Device Settings

In here filter on Orders in the Category column

Require orders to have a minimum quantity - This setting allows you to set a minimum quantity on an order.  Enter the quantity required under the value column

Require orders to have a minimum value - This allows to set a value for an order.  Enter the minimum value in the value column

On the tablet it will display like this.  If you enter a value less than the minimum value or quantity, it will prompt the user when closing the call.  It won't allow the user to close the call until these have been met.  

To enforce this further you can activate the following setting 'Strictly enforce order minimums' The Rep won't be allowed to exit the call until it is corrected.