Find my approach as reference below and stored in attached workbook version 10.0.
I "pivoted" the table and defined the following Calculated field:
Chart Type (pivot): if [Base Tax]="Base Amount" then [Charge Type]
else "Taxes" END
Billing Breakdown Average.twbx 15.3 KB
Try pivoting your data in Tableau:
Highlight 'Base Amount' and 'Tax Amount' on you data within Tableau once you have added your data source.
Click on the Drop Down arrow of your 'Tax Amount' and select 'Pivot'.
Now you can start placing your pills, as per the picture below:
Hope this helps.