Summing a Calculated Field

I have data at a store level that is repeated for each item int he store in the dataset.  Each store has the same value regardless of the item in the Sum of MOD LINEAR column.  In the example, this data is 1,920.  At the total for store 1060 and store 1527, the total is 55,680, which is a summation of 1,920 for each item.  I only want the total line for the store to show 1,920 until it gets to the grand total, which should be 3,840 (two stores at 1,920 * 2).  Any suggestions on how to write a formula to get it to return these calculations would be apprecitated.  Thank you.