I cut a 48" roll of tape down to 24" once. Used a 10" miter saw with a fine tooth blade. I had to turn the roll to cut all the way through it, so the cut wasn't perfectly straight. It was a little messy, but the tape didn't fuse together and is perfectly usable.
I have a new idea to try now though. My brother-in-law has a vertical band saw. I ordered a razor sharp knife edge band saw blade to fit it. In theory I should be able to slice right through rolls of tape, vinyl, & other rolled media.