See the attached for an implementation of both techniques (top N and KPI) using the superstore sales sample data. Both techniques use table calculations, for the top N we use the INDEX() calculation and for generating the KPI we get the Percent of Total using the basic Quick Table Calculation, with some customization.
Let me know if you have any questions,
top N and KPI.twbx.zip 1.1 MB
Thanks for the help Jonathan!
Another part of my question was - I need to show just a KPI (with no text, labels, etc.) on a dashboard.
For example I could use the "14.54%" from Office Machines to control the shape of the KPI with no accompanying data.
I have learned from another source how to do this by filtering / hiding information as required, so I should be OK now!