Untitled

var isfirst = 1, lastelm;
$("#divid").find("*").each(function() {
    var cur = $(this);
    if(parseInt(cur.css("margin-top")) > 0 && isfirst == 1) {
        cur.css("margin-top", 0);
        isfirst = 0;
    }
    if(parseInt(cur.css("margin-bottom")) > 0) {
        lastelm = cur;
    }
});
lastelm.css("margin-bottom", 0);

<html>
   <body>
      <p>
        <p>A<p>
        <p>B<p>
        <p style="margin: 10px;">C<p>
        <p style="margin: 10px;">C<p>
        <p>D<p>
      </p>
      <script>
         $(document).ready(function(){
            $('p').filter(function(){
                return this.style.margin != '';
            }).last().css('color','red');

         });

     </script>
  <body>

#my-element > *:first-child {
    margin-top: 0;
}

#my-element > *:last-child {
    margin-bottom: 0;
}