Use the following steps to calculate the percent of total for the Sales Furniture, Sales Office Supplies, and Sales Technology measure fields:

1. Select Analysis > Create Calculated Field.
2. Name the calculation. In the example workbook, the calculation is named "Sales % Furniture".
3. In the formula field, create a calculated field similar to the following and click OK: 

4. SUM( [Sales Furniture] ) / SUM( [Sales] )

5. Repeat steps 1-3 for each new percentage.
6. Create a new worksheet to display the percentage measures. In the example workbook, this worksheet is named "%Measures".
7. Make a new dashboard (Dashboard > New) and drag the Measures and %Measures worksheets onto the view side by side. 

To view these steps in action, see the video below:
Note: Video is silent.