tangor - 4:14 pm on Sep 9, 2013 (gmt 0)
As an interim measure for one of my clients we adopted a "free shipping on items x dollars or more" statement, then for items less than that performed the calculations as ordinary postal rates. That was used until client sprang for the coder dollars to automagically factor cost/markup/shipping ... and after that was finally done the client realized the first solution was the better choice.
There's no such thing as free shipping. Even the customer knows that. However as a marketing device "free shipping" sounds so much better. Client eventually published best price and offered calculated shipping... and in most cases still came in under the competition's "free shipping" pricing.
Every business is a bit different... what works for one may not work for another.