In order to see profitability in categories, you would need to group ASINs together inside the Product Manager.
Once you have applied the specific labels to the products it will group them together inside the Profits Dashboard page.
You would need to scroll down to the Product Comparison section inside of the Profits Dashboard and select filters then "By Labels" is where you would search the labels you just created.
Now you can view the following data inside the Product Comparison:
Units Sold
Orders
Unique Buyers
Gift Wraps
Revenue
Sales
Custom Revenue
Taxes
Costs
Promotions
Product Promos
Shipping Promos
Refunds
Amazon Fees
PPC Spend
PPC Sales
PPC Units Ordered
PPC ACoS
PPC TACoS
Inv. Reimburse
Other Trans.
Misc. Fees
Custom Expenses
Cost of Goods
Net Profit
Margins