Hiding Handling charges is not against any rules that I am aware of. You can display it seperate or combine it all with the quoted shipping charge, wheather it be Flat or Calculated. I do it all the time and its built right into Auctiva.
I'm not sure where Hidden Charges came from? I'm sure that is against the business ethnic code no? Saying something is $19.95 + $4.95 S&H and then when the customer gets the final invoice its $19.95 + $4.95 S&H + $10.00 Customer Appreciation Fee probably would not be allowed.
But you are under no obligation to share with a customer what your 'Handling' costs are.