How to add tags when posting via PHP

Hey, I’m trying to figure out how to add tags/keywords (these terms are interchangeable, right?) when posting to my blog via PHP. Here is the function I’m using to post right now. It’s working great, but I want to programmatically add tags. Many thanks:

<?php
//DEFINE
function wpPostXMLRPC($title,$body,$rpcurl,$username,$password,$categories=array(1)){
$categories = implode(“,”, $categories);
$XML = “<title>$title</title>”.
“<category>$categories</category>”.
$body;
$params = array(”,”,$username,$password,$XML,1);
$request = xmlrpc_encode_request(‘blogger.newPost’,$params);
$ch = curl_init();
curl_setopt($ch, CURLOPT_POSTFIELDS, $request);
curl_setopt($ch, CURLOPT_URL, $rpcurl);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_TIMEOUT, 1);
curl_exec($ch);
curl_close($ch);
}
//START
wpPostXMLRPC(“May 14, 2011″,allMyHTMLGoesHere,”https://thisiswhatwecareabout.com/xmlrpc.php&#8221;,admin,fakePassword);