Dose any one know how to properly roll up a charging cable to a MacBook Air?

So I've had my lap top for a while now and the cord covering just split open on me exposing the inside wires. it happens to me every time I get an apple charger for anything. Iphone, ipod, ipad... anything apple their chargers just always seem to split on me. I always have to go out and buy $30-40 chargers to keep them from spliting. I was just wondering if anyone has solved this problem yet. I roll my cords up in a circle and twist them so they are all in a uniform cirlce. The cords always seem to split right at the ends never in the middle. If you could let me know how you guys keep your cords from spliting open. This charger lasted me maybe two years maybe two and a half... somewhere between two and three years then it split on me. I don't know if thats normal for a cord that old to split open or should it have lasted a bit longer.