Okay, This is how I do it and many shops. You know the way fabric is made that it will tear easily because there is a warp and the weft in the way material is made.
Use your scissors to cut exactly the point 2 1/2 yds. that is the half way point right. Now is the time to be brave grab to two ends you have cut and it will tear completely evenly. Trust me. If you are unsure, do it on another piece of material. I do this all the time, have been sewing for upteen years. LOL
Elle