See comments above for answer. It is working great.

Imagine a form with three uls (as sections). Each section has several 'li checkbox /li' and the last one says Check/Uncheck All. Here is the code, which will change all checkboxes in same ul.

$(document).ready(function(){
  $('.check-all').change( function(){
    $(this).closest("ul").find('input[type=checkbox]').attr('checked', $(this).attr('checked') || false );
  });
});

I hope this helps someone -- and please correct me where I'm wrong!

// FIND PARENT WITH TAG
function findParentWithTag(tagToFind:String) {
    return findParentWithTag(tagToFind, this.gameObject);
}
function findParentWithTag(tagToFind:String, startingObject:GameObject) {
    var parent = startingObject.transform.parent;
    while (parent != null) { 
       if (parent.tag == tagToFind) {
         return parent.gameObject as GameObject;
       }
       parent = parent.transform.parent;
    }
    return null;
}