I would try applying floats to the divs within the media query, this ill require each div to have an id. By applying the float to the class as you suggest in your question you will float all of your div to the left.
@media (min-width: 980px)
{
.col_5 {
width: 20%;
position: relative;
}
#box1 {
float: left;
}
#box2 {
float: right;
}
#box3 {
float: left;
}
#box4 {
float: right;
}
#box5 {
float: left;
}
}
Then apply these id's to the boxes as follows:
<div>
<div id="box1" class="col_5 col-xs-6">box 1 </div>
<div id="box2" class="col_5 col-xs-6">box 2</div>
<div id="box3" class="col_5 col-xs-6">box 3 </div>
<div id="box4" class="col_5 col-xs-6">box 4</div>
<div id="box5" class="col_5">box 5</div>
</div>
I hope that this helps!