If you don't feel like going procedural to get the HTML output, you can simple use this alternative:
<?php
$html = <<<HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head><title>title</title></head>
<body>
<p>paragraph <br />
text</p>
</body></html>
HTML;
$tidy = new tidy;
$tidy->parseString($html);
$tidy->cleanRepair();
echo $tidy->html()->value;
?>
You can even more simply access the HTML output via this:
<?php
echo $tidy->value;
?>