jQuery.fn.dataTableExt.aTypes.push(  
    function(sData) {
        sData = sData.replace(/^[^0123456789$£.,-]*/, "").replace(/[^0123456789$£.,-]$/, "");
        var sValidChars = "0123456789.-,";  
        var Char;  
        
        /* Check the numeric part */  
        for ( i=1 ; i<sData.length ; i++ ) {   
            Char = sData.charAt(i);   
            if (sValidChars.indexOf(Char) == -1) {
                return null;  
            }  
        }  
          
        /* Check prefixed by currency */  
        if ( sData.charAt(0) == '$' || sData.charAt(0) == '£' ) {
            return 'currency';  
        }

        return null;  
    }  
);

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 the currency sign */
	x = x.substring(1);
	y = y.substring(1);
	
	/* 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 the currency sign */
	x = x.substring( 1 );
	y = y.substring( 1 );
	
	/* Parse and return */
	x = parseFloat( x );
	y = parseFloat( y );
	return y - x;
};