Measure for matrix visual that rolls up values from child rows to parent rows.

[AndyB87]

I'm trying to write a measure for a matrix visualization that will roll up a calculation of a percentage from child rows to parent rows. 

I have a data model with a fact table called 'retailSales' that contains transaction data and a dimension table called 'product' that contains product information. Our products are divided into a taxonomy of categories, so the product table has fields for [masterCategory], [category], and [subcategory]. I'm putting together an analysis of our product categories. I have a matrix where the rows drill down from master category to category to subcategory. I have a column that calculates dollar sales for each row. I'd like to write a measure that calculates each row's dollar sales value as a % of its parent row subtotal (and % of total sales for each master category). It should look like the following example:

So far, I have a measure that successfully calculates each row's % share of total sales, but it doesn't roll up percentages from child rows to parent rows the way I want. It calculates a child row as a % of the total rather than its parent. It looks like this:

CategoryShare = 
DIVIDE(
    SUM( retailSales[soldPrice] ),
    CALCULATE(
        SUM( retailSales[soldPrice] ),
        ALLSELECTED( product )
    )
)

Any thoughts on how to write a measure that does what I'm looking for?

[some_bih]

Hi @AndyB87 try to use ALLEXCEPT for your column (I guess [category],) as shown in example https://www.sqlbi.com/articles/using-allexcept-versus-all-and-values/  I hope this help