Of socks and men

Microsoft have invested in making their OLAP tools do everything. Some of the functionality is, however, not intuitive and NonLeafDatHidden is one of those gotchas.
If you set the MembersWithData property of a dimension to NonLeafDataHidden then, as it says on the tin, the data associated with a node in a hierarchy disappears from view. What is not obvious, unless you get a calculator out, is that the data values remain included in the totals. Thus if a manager (e.g. Stephen Yang from the AdventureWorks example) has sales in his own name of $1M then his personal sales will remain in the grand total of $80.45M even if the MembersWithData property is set to NonLeafDataHidden.