I believe you will need to create measures for each dimension value you would like to color differently. For example, for furniture, the calculated field would look similar to the following:
If [Category] = "Furniture" then [Sales] End
Category being the field that contains the value Furniture and Sales being the measure populating the crosstab.
Repeat this for each Dimension value you would like to independently color (Office Supplies and Technology).
Next, you can create a calculated field to color each individual measure we just created with a formula similar to the following:
If Sum([Furniture Sales]) >= 100 OR Sum([Furniture Sales]) <= 120 then "Lite Green"
Elseif Sum([Furniture Sales > 120 then "Dark Green"
Repeat a similar formula with the desired changes for each dimension value (Office Supplies and Technology).
From here the following link details the final steps. This link also contains a sample workbook: