You will always get hit with charges from courier companies (DHL, Fedex, UPS) because their systems are automated to calculate and add duties, taxes & brokerage - so there is no delay to next day or two day shipping options. The package never hits a customs agent at all. No convenience fee- it is a fee for brokering your package, again, necessary to have it escape any delay or scrutiny by the customs service.
For regular mail like USPS, mostly you will not (unless it is a fairly large $$ order).
When using a courier, I ask for value to be marked as $20. Most will do it. That is the threshold for duties, taxes and the like.