For Simple tables (Tablix) the alternate color formula is:
=iif(rownumber(nothing) Mod 2, "White", "#f5f4e9")
I have a table matrix that I would like to alternate the row color, the problem is that multiple cells shift color around due to the matrix data grouping. I found a workaround.
I will not display report data images due to data privacy, but I will explain the process as much as I can.
First; create a column in the report outside the grouping, I recomend at the end of the report; this will be our guide:
add the following expression: Remember the Field name we will call it TEXTBOX39
=iif(RunningValue(Fields!THISISTHEROWGROUPINGTHATALTERNATES.Value,CountDistinct,Nothing) Mod 2, "White", "#f5f4e9")
Keep in mind that THISISTHEROWGROUPINGTHATALTERNATES references A in the image below; (Inner Group Field Value)
Now hide the column
And that should do it :)