$(document).ready(function() 
    { 
        $("#month-data").tablesorter();
    } 
); 

// add parser through the tablesorter addParser method 
$.tablesorter.addParser({ 
    // set a unique id 
    id: 'thousands',
    is: function(s) { 
        // return false so this parser is not auto detected 
        return false; 
    }, 
    format: function(s) {
        // format your data for normalization 
        return s.replace('$','').replace(/,/g,'');
    }, 
    // set type, either numeric or text 
    type: 'numeric' 
}); 

$(function() {
    $("table").tablesorter({
        headers: {
            8: {//zero-based column index
                sorter:'thousands'
            }
        }
    });
});