Cash drawers in Starch Up keep track of all transactions that are run through a given work station. Multiple work stations can be configured to use the same cash drawer. To select the cash drawer associated with a given workstation go to the home page, click into the workstation settings in the top right hand corner and then choose the drawer associated with the work station.
To set up a cash drawer go to setup -> settings -> cash drawer section in the lower right hand corner. When setting up the drawer the Name value is what will be shown in the workstation settings drop down. The default amount will be the starting cash balence, and will be what things reset to when you do a reset after running a drawer count.