Complex calculations on a pivot table

I have a large database and pivot table, with monthly data. I created a sample database to show you the problem I am having.

The underlying data looks something like this (just clipped a few lines)

The resulting pivot returns this

What I want to do is display only the accounts where sales in 2 of the last 3 months are 5 or less.

I tried calculated items - but on my original pivot table this results in an error " too many records" 

I've tried other iterations, none work without a ton of manual intervention.

Can someone point me in the direction of a solution or a hack?