Listing A: Query That Returns the Puzzle Solution
WITH
  SET [LargestCustomer] AS 'TOPCOUNT( [Customers].[Name].MEMBERS, 1, [Store Sales] )'
  MEMBER [Measures].[MaxSales] AS '([LargestCustomer].item(0).item(0), [Store Sales])'
SELECT { [Store Sales] } ON COLUMNS,
  FILTER( [Customers].[Name].MEMBERS, ([Store Sales]) >= (0.05 * [MaxSales]) ) ON ROWS
FROM Sales