uncheck checkbox on click

uncheck checkbox on click

the idee is
When the collapsible groups close all the checkboxes must be unchecked.

<div data-role="collapsible">
    <h2 role="title"> Na Toren 1</h2>
        <fieldset data-role="controlgroup" data-inset="true">
                 <input type="checkbox" name="checkbox-13" id="13" class="custom" />
                 <label for="13" style="color:#F7AC0A">
                     T 13 <br/> S 106
                 </label>
                 <input type="checkbox" name="checkbox-23" id="23" class="custom" />
                 <label for="23" style="color:#F7AC0A">
                     T 23 <br/> S 106
                 </label>
                 <input type="checkbox" name="checkbox-05" id="05" class="custom" />
                 <label for="05" style="color:#F7AC0A">
                     T 05 <br/> S 91
                 </label>
    </fieldset>

-------------------------------------------------

 $('h2[role=title]').click(function () {
        $('input[type=checkbox]').each(function () {
            if (this.checked) {
                this.attr("checked",false).checkboxradio("refresh");
            }
        });
    });

i'm using this script but i get an error "this.attr is not a function".
can sombody help me.