I chop a point on the peg and then bevel it 1/3 of its length which is twice the thickness of the beam. But there is no taper after that, no intentional taper at least but generally those pegs are so irregular. The point and bevel I see as guiding the peg into the off set hole of the tenon and then gradually initiating the draw so I wouldn't characterize the action as wedging at any time. A tapered peg though that would surely be a wedge too. What's the point of a tapered peg?