<?php
class Redirect{
    /**
     * Путь к файлу xml и название
     * @var string
     */
    static protected $_XPath = 'links.xml';
    /**
     * Массив ссылок
     * @var array
     */
    static public $links = array(
        1 => 'http://1.ru',
        2 => 'http://2.ru',
        3 => 'http://3.ru',
        4 => 'http://4.ru',
        5 => 'http://5.ru',
    );

    static public function RedirectTo(){
        $xml = simplexml_load_file(self::$_XPath);
        $current_id = (int)$xml->id;
        $current_link = self::$links[$current_id];
        if ($current_id < count(self::$links)){
            $current_id++;
            $xml->id = $current_id;
            $xml->asXML(self::$_XPath);
        }
        elseif ($current_id == count(self::$links)) {
          $current_id = 1;
          $xml->id = $current_id;
          $xml->asXML(self::$_XPath);
        }
        return header( 'Location: ' . $current_link );
    }
}
Redirect::RedirectTo();
?>
 

<?xml version="1.0" encoding="UTF-8"?>
<current>
    <id>3</id>
</current>