The reports are determined by how the combo is set up. 

This might be a little confusing so let me use an example here:
 
 

#1: Combo Type
#2: Price of combo determined be Prevailing or Reduced Price from #1.
 
#3: The Combo Priced As

Single Item Combo
A discount to each item in the combo

#5: Sales Category for Combo

 
#6: Entree Count - This is the cover count amount for this Combo.