I have noticed that Import/Customs duties are always charged to the sender. For all parcels we send the recipient is responsible for paying these (I would imagine it is the same for a lot of people).
I fixed this by changing SENDER to RECIPIENT on line 435 in model/shipping/carrier/fedex/rate.php however it would be great to have an option in admin to set this.
We got caught out and had to pay import for a few parcels before we caught this.
Keep up the good work!