That's not going to do what you want, regardless of whether you use bindParam() or bindValue().
A SQL query parameter takes the place of one value only. You can't bind a string containing commas and have it be interpreted as several values. You need one parameter placeholder for each distinct value in your list.
Also, you don't need to bind parameter value at all with PDO. You can pass an array to execute(). In this case, I'd use positional parameters instead of named parameters. PDO supports both, but don't mix them in one query.
$query = "SELECT * FROM `votes` WHERE `tags` IN (?, ?, ?)";
$stmt = $dbh->prepare($query);
$params = explode(', ', 'one, two, three');