I don't roll it, or do it in sections.
I fold the whole shebang in half (all 3 yards- or whatever), making sure the selvages are lined up.
Then fold that in that half, again making sure everything is lined up and flat, the inner folds are not getting yanked out of position, and everything is taut.
I keep doing that until I've got less than 24", recheck everything again, position the ruler, and cut.
Hope that helps. ;-)
eta: Depending on your border plans, you can keep the fabric folded in half (by the width) for this whole process. That means each cut will get you 2 borders, and still leave you with an extra contiguous piece in the center.
Or you can cut the yardage down the middle (width - the fold when it comes off the bolt) and work with it that way.
Again, it depends on the planned width of your border.