anchor.diff:        del.prop('checked', !el.prop('checked'));
         $("#total_field").html(calculateTotal());
       });
  +    $(document).on("click", "#unselect_all", function() {
  +      select_all(false);
  +    });
  +    $(document).on("click", "#select_all", function() {
  +      select_all(true);
  +    });
  +    function select_all(check_on) {
  +      $(".anon").each(function() {
  +        el = $(this);
  +        if (el.prop('checked') != check_on) {
  +          el.trigger("click");
  +        }
  +      });
  +    }
       $(document).ready(function() {
         // calculate initially
         $("#total_field").html(calculateTotal());
  
positive.code:       var total_cents = 0;
        all_values.each(function() {
          var el = $(this);
          var not_included = findDeleteCheck(el);
          if (not_included.prop('checked')) {
          }
          else
          {
            total_cents += parseInt(el.data("cents"));
          }
        });
  
negative.code:         <th></th>
          <th></th>
          <th></th>
          <th>
            <a href="#" id="unselect_all">Unselect All</a>/<a href="#" id="select_all">Select All</a>
          </th>
        </tr>
      </thead>
      <tbody>
  