Top 10% with filter

I have a spreadsheet of work order information.

I want to pull the top 10% of work orders based on some slicers I created.

I created the following measures to display rank and percentile rank.  I can filter to the top 10 work orders based on rank, but if i try to to filter by percentile rank, I don't get the desired output.

Rank = RANKX(ALLSELECTED(womaster),CALCULATE(SUM(womaster[WOtotal])))
Pct Rank = [Rank] / COUNTROWS(ALLSELECTED(womaster))

If i put on a slicer for all work orders from a certail category, I get the appropriate rank and percentile rank displayed for every value in the table, but once i filter to top 10%, I get more rows than is appropriate.  For example,  with no filter, there are 50 work orders in the top 10 percent, but when I apply the filter, i get 96 work orders.  To be clear, the problem isn't with the slicer - the problem is the filter.  

Any one have any ideas how i can fix this?