I just rinse using soap and water for water-based rollers. For oil-based paint, I use some paint remover worked into the roller, and cleaned out with whatever solvent the paint remover said to use as a follow-up to using the remover on anything.

Frankly, it is a lot easier and not a lot more $$ to just get a new roller, when you consider the time and effort and $$ to buy the removal chemicals.