It really depends on you. You will definitely have a gentler Master-Cleanse if you taper off. But if you are like me, and prefer to get things over with even if it means more pain, you might prefer to do the Master-Cleanse the way I did it the first time around - which was completely cold turkey. I broke a 20 year coffee addiction with my first Master-Cleanse (in August 2003). It was VERY hard though - days one and two I fell asleep in my chair at work several times. I also had to pull over on my way to work to rest!!!
On day 3, I was so toxic I took the day off from work to spend in bed!!! I posted all this here on the MC forum, so if you go back to the archives for late August 2003 you can read all about it in gory detail.
Really, there are pros and cons to both ways of doing it and it is truly your choice.