Have placed a number of orders in the last couple of years, and my experience has been like MamaBear's - sometimes get charged duty, most times not.
Have even had two packages arrive from different shops on the same day, one got duty charged the other didn't.
No idea what the rules really are - glad when there aren't additional charges but am always prepared to pay the import duty taxes.
I have no idea what the $5 service fee would be from the delivery person!