There's nothing specific about HANA
with regard of Top N filters or such.
Could you please write your [Rank] calculation?
Where it is going from? Datasource? Tableau?
If latter, is it just RANK(...) of something, or else?
There are two ways of doing Top N filters in Tableau:
1) Top N Dimension Filter
2) RANK() Table Calculation Filter
The desired Grand Totals (Top N only)
would come from the former, not the latter.
Hope it could help.