You should be able to set up your Summary Criteria using Expressions and appropriate logical OR operators. I obviously don’t have the Customer Tier field, but setting up your Summary Criteria something like this should work:
You would of course replace my use of the Customer Status field with your Customer Tier field, and you would need to find the appropriate value for each Tier to place in the Description. Then use the Parens and OR operators to group the conditions appropriately.
If you set these up correctly, then any Customer showing up in your results should be in the incorrect Tier.