Grouping posts in pairs

Is there anyway to group posts in pairs?
I have a category with 5 posts like this:

<div class=”col6″>
<p>post_1</>
</div>
<div class=”col6″>
<p>post_2</>
</div>
<div class=”col6″>
<p>post_3</>
</div>
<div class=”col6″>
<p>post_4</>
</div>
<div class=”col6″>
<p>post_5</>
</div>

And I need to group them in pairs as follow:
<div class=”row”>
<div class=”col6″>
<p>post_1</>
</div>
<div class=”col6″>
<p>post_2</>
</div>
</div>
<div class=”row”>
<div class=”col6″>
<p>post_3</>
</div>
<div class=”col6″>
<p>post_4</>
</div>
</div>
<div class=”row”>
<div class=”col6″>
<p>post_5</>
</div>
</div>

I have tried using a var that counts the post and if is odd opens <div class=”row”> and if is even closes the tag…. the problem comes with the last post which is even so the tag doesn’t close…

Any help would be great!!

Thanks!!