Simple and to the POINT:
jQuery - Upon Clicking a button or div or a label element. Check off all checkboxes on the page. Keep in mind you'll have to adjust :checkbox to make it more specific.
jQuery("#My-Button").click(function() {
jQuery(':checkbox').each(function() {
if(this.checked == true) {
this.checked = false;
} else {
this.checked = true;
}
});
});