Yes I'm not sure either, I can see in developer tools, there is a cookie called "currency" however I can't seem to override this.
$opts = array(
'http'=>array(
'method'=>"POST",
'header'=>array("Accept-language: en",
"Cookie: currency=EUR",
"Custom-Header: value")
)
);
$context = stream_context_create($opts);
$file = file_get_contents($url, false, $context);
echo $file;