SSAS Feature to hold confidential data
This is an overly broad question but SSAS has security features that allow you to shield data for certain users.

You should look into Roles and Permissions.

Since you are talking about shielding costs you probably just want to limit access to certain measures so you're probably looking for Grant custom access to cell data which limit access to the values:


  Cell security is used to allow or deny access to measure data within a
  cube.  Cell permissions apply to data inside the cell, and not to its
  metadata. Notice how the cell is still visible in the results of a
  query, displaying a value of #N/A instead of the actual cell value.


If you want to hide the fact that the measure exists you need to look at Grant custom access to dimension data


  In Grant custom access to cell data (Analysis Services), it was
  explained that fully hiding all visual aspects of a measure, and not
  just its cell data, requires permissions on dimension members. This
  section explains how to deny access to the object metadata of a
  measure.