See attached. I did this in 8.2 since you didn't specify a version.
If you are working in 9.0 or higher, you can do the same sort of thing with LOD calcs, but here I did table calcs.
I just made a bar sheet to keep this simple. Not a map. Having a map doesn't change how you'll do this. You can apply the same technique to your application.
In the tooltips you'll see a biggest-item, and the sales amount for that item. You can see it changes from state to state, but remains the same throughout all the items sold in that state.
But I'll bet you don't have the table calc "compute using" set like I did in my example.