jQuery.fn.dataTableExt.oSort['currency-asc'] = function(a,b) {
    /* Remove any commas (assumes that if present all strings will have a fixed number of d.p) */
    var x = a == "-" ? 0 : a.replace( /,/g, "" );
    var y = b == "-" ? 0 : b.replace( /,/g, "" );
    
    // remove (inc VAT) or (exc VAT) and <span></span>
    x = x.substring(7, x.length-17);
    y = y.substring(7, y.length-17);
    
    /* Parse and return */
    x = parseFloat( x );
    y = parseFloat( y );
    return x - y;
};

jQuery.fn.dataTableExt.oSort['currency-desc'] = function(a,b) {
    /* Remove any commas (assumes that if present all strings will have a fixed number of d.p) */
    var x = a == "-" ? 0 : a.replace( /,/g, "" );
    var y = b == "-" ? 0 : b.replace( /,/g, "" );
    
    // remove (inc VAT) or (exc VAT) and <span></span>
    x = x.substring(7, x.length-17);
    y = y.substring(7, y.length-17);
    
    /* Parse and return */
    x = parseFloat( x );
    y = parseFloat( y );
    
    return y - x;
};