Once you have an empty matrix set to your desired dataset right click in the data area to add in extra rows.
Add in the desired Column Grouping once you have added in all the rows you'll need (Note: The added row will alway appear at the bottom and Right Click - Delete will delete the desired Row), now the Rows are essentially just textboxes (since you have no Row Grouping) so you can write in a description of what the row will represent
Now the trick here is the expressions in the data fields
=Sum(CInt(IIF(FieldToSumOver = "DescriptionOfFieldOrCode", ValueToSum, Nothing)))
In the example this is the "Sales for North America" data expression is:
=Sum(CInt(IIF(Fields!Continent.Value = "North America", Fields!TotalDue.Value, Nothing)))
You need to use the CInt() or CDbl() because for some reason the IIF() function converts the values to text, this is what the above report looks like in Report Manager
This approach only works when there is a fixed amount of possible row values, It's a good method for Profit and Loss reports.
