If you are going to rip the borders, do not just make them 5 inches. I would make them more like 7 inches, then cut off 1 inch from each side to get rid of the raggedy edges.
A better solution would be to pull a thread to get very even edges that would be straight of grain. To see my tutorial on this method see:
http://www.quiltingboard.com/t-114232-1.htm
Using this method, you will not waste the torn edges. It may be a bit more time consuming, but it will be much better for the edges of your fabric, and you won't have to cut any waste off.