jQuery: Auto checked table when all checkboxes are checked

I'm fairly new in jQuery. Basically I have a few tables and I have to make last checkbox for each table checked when all of the elements of a table are checked. Here is a simple demo that is the result that I want.

Demo: Fiddle

So far this is what I did, but it still checked for my last checkbox although the elements of that field are not checked all of them.

$('table tr:last-child input:checkbox').closest('table').find('input:checkbox').each(function() {
        if ($(this).is(":checked")) {
           $('table tr:last-child input:checkbox').prop('checked',true);
        }
});