Hi,
Create two variable,one is your particular material,another one is for remaining material
var1
=If([Main Query].[L01 Product Category - D]="White";"White";If([Main Query].[L01 Product Category - D] = "Hispanic";"Hispanic";If([Main Query].[L01 Product Category - D]="Black";"Black"; [Var2])))
Var2
=If([Main Query].[L01 Product Category - D] InList("White";"Hispanic";"Black");"Exist";"Other" )
drag first variable in your table with corresponding measure..