DAX/Powerpivot expert excel needed for quick task I am stuck with

Job ID: 34842906

Budget: $10 – $30 USD

Hi,
I have got stuck on a Powerpivot task, and need someone to let me know the correct formula. I just want to sum the rows below a subtotal. At the moment it keepts recalculating dynamically.

Each row is calculating the mix which is margin - price impact - volume. The issue is that volume is calculated dynamically so a new average unit cost is calculated for all profuct groups when I use the "All" function, where as I just want to add the numbers/rows underneath, using the average unit cost at those levels.

So simply I want to add the rows below without it recalculating and working out a new average when I use the ALL function, I have tried Sumx but to do success.

I believe for a dax expert this is an easy issue to resolve.
Related categories: Excel Power BI