From http://www.wearesicc.com/quick-tips-5-column-layout-with-twitter-bootstrap/

bootstrap-5col.css

.col-xs-15,
.col-sm-15,
.col-md-15,
.col-lg-15 {
    position: relative;
    min-height: 1px;
    padding-right: 10px;
    padding-left: 10px;
}
.col-xs-15 {
    width: 20%;
    float: left;
}
@media (min-width: 768px) {
.col-sm-15 {
        width: 20%;
        float: left;
    }
}
@media (min-width: 992px) {
    .col-md-15 {
        width: 20%;
        float: left;
    }
}
@media (min-width: 1200px) {
    .col-lg-15 {
        width: 20%;
        float: left;
    }
}