Yes, tapered endmills can be the solution if the mold has simple contours. Internal corners can be problematic if the designer is not aware of the limitations of a tapered tool, because a tapered tool lends itself to cutting corners with a variable radius.
Other times, you may have to use ballnose endmills and simulate the taper by going round and round with very shallow changes in depth between passes.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)