I just asked this at local quilt shop yesterday - she said "No problem, lots of my customers have me save empty cardboard from fabric bolts just for that purpose", so I guess its fine to do. I wrap my fabric around a 12 x 24 ruler, then slip the ruler out & fold once so the fabric fits on my shelf. I keep it out of the sun so the fold doesn't fade.
Good luck with whatever method you use to easily keep your stash.