I just started rolling my own bulk film to use in my collection of cameras, and I definitely suggest to cut a slightly tapered leader instead of cutting straight across.
Just this past month, I brought a bunch with me for a trip up to Wisconsin, and had cut them straight across. I found too late that my camera's take-up spool only accommodated the lower third or so of the leader, so I had to hastily borrow a friend's nail scissors and recut the leaders of all my rolls!