The best report to see your department level inventory over a period of time is located under REPORTS>NON FUEL INVENTORY> DEPARTMENT INVENTORY REPORT. A sample report is shown below.
Report shows OPENing level in the first day of date range selected and all PURCHASED during the date range, All SOLD during dates specified, any TAKE INVENTORY that was done and INVENTORY ADJUSTMENTS that were made. The CLOSE figure is the closing value as of the last day of the date range chosen.
Another good report to troubleshoot MARGIN issues and PURCHASES is in REPORTS> NON FUEL INVENTORY>NONFUEL INVOICES BY STATION/DEPARTMENT
This report shows any issues with margins entered on invoices and errors with purchases.