right to left matrix

Well this isn't perfect, but it's the closest I have come.

1) In Power Query, create the layout of the matrix using:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("fdCxCoAwDATQf8ncweYi6OwnOJYiFcRREB38e6GDFMI5JnkcR1ISlSBTubb9OJ+4zPf6De1BckgCRtXRnlE4OjYbZQW00oFRdTR2zOI3FqwBKjVG1VEwCkcjo+Zo+y1jXU1yfgE=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Amount = _t, #"Sub-Category" = _t, Category = _t]),
    OrignalTable = Table.TransformColumnTypes(Source,{{"Amount", Int64.Type}, {"Sub-Category", type text}, {"Category", type text}}),
    #"Removed Other Columns" = Table.SelectColumns(OrignalTable,{"Category"}),
    #"Removed Duplicates" = Table.Distinct(#"Removed Other Columns"),
    #"Added Index" = Table.AddIndexColumn(#"Removed Duplicates", "Index", 1, 1, Int64.Type),
    CatIndex = Table.RenameColumns(#"Added Index",{{"Index", "CatIndex"}}),
    #"Merged Queries" = Table.NestedJoin(CatIndex, {"Category"}, OrignalTable, {"Category"}, "CatIndex.1", JoinKind.LeftOuter),
    #"Expanded CatIndex.1" = Table.ExpandTableColumn(#"Merged Queries", "CatIndex.1", {"Sub-Category"}, {"Sub-Category"}),
    #"Added Index1" = Table.AddIndexColumn(#"Expanded CatIndex.1", "Index", 1, 1, Int64.Type),
    #"Added Custom" = Table.AddColumn(#"Added Index1", "Custom", each [CatIndex] + [Index]/1000),
    #"Removed Columns" = Table.RemoveColumns(#"Added Custom",{"Index"}),
    SubCatIndex = Table.RenameColumns(#"Removed Columns",{{"Custom", "SubCatIndex"}}),
    #"Removed Other Columns1" = Table.SelectColumns(SubCatIndex,{"Sub-Category", "SubCatIndex"}),
    #"Renamed Columns" = Table.RenameColumns(#"Removed Other Columns1",{{"SubCatIndex", "CatIndex"}, {"Sub-Category", "Category"}}),
    #"Appended Query" = Table.Combine({#"Renamed Columns", #"CatIndex"}),
    #"Sorted Rows" = Table.Sort(#"Appended Query",{{"CatIndex", Order.Ascending}})
in
    #"Sorted Rows"

which gets you 

 Create an active relationship between Matrix Category and the orginal table Category. Create an inactive relationship between Matrix Category and the original table SubCategory.

Then these measures:

Sum Value = SUM(OrigTable[Amount])

Amount =
VAR SubCat =
    CALCULATE (
        [Sum Value],
        USERELATIONSHIP ( 'Matrix Structure'[Category], OrigTable[Sub-Category] )
    )
RETURN
    IF (
        ISINSCOPE ( 'Matrix Structure'[Category] ),
        [Sum Value] + SubCat,
        "Total "
            & FORMAT ( DIVIDE ( [Sum Value] + SubCat, 2 ), "#,##0" )
    )

Create a table visual with the field from the matrix table & the [Amount] measure, add conditional formatting and you get:

 I've attached the sample PBIX file