Instead of a static class property, you could use a PHP session:
class progress {
public function __construct() {
session_start();
}
public function getTotal() {
return $_SESSION[ 'total' ];
}
public static function setTotal() {
$_SESSION[ 'total' ] = '123';
}
}
If you’re doing more complex stuff, a session wrapper like Symfony’s might be a good idea.