Add an additional amount to the Auspost extension

Hi All, I have been playing around with opencart for the last few weeks and I'm really enjoying it, I have found these forums to be very handy.
This is what I have so far: www.lockupmyhome.com.au
I initially had a few issues with the auspost extension not working but seem to have it resolved (replaced the code)
I just have one small issue remaining I would like to add an extra $3.25 to every postage calculation to cover the registration cost. I thought this was an option in the extension but there are no options to include it (as far as I can see). I'm just wondering if there is an easy way of doing this by hardcoding it into the auspost.php module?
Coming from a vba background I was just hoping I could add +3.25 to one of the variables or something somewhere in the code but I wouldn't know where to begin. Any advice would be greatly appreciated as I would like to know how it is actually done rather than buying a different extension etc.

Thanks
Justin

<?php
class ModelShippingAusPost extends Model {
public function getQuote($address) {
$this->load->language('shipping/auspost');

$query = $this->db->query("SELECT * FROM " . DB_PREFIX . "zone_to_geo_zone WHERE geo_zone_id = '" . (int)$this->config->get('auspost_geo_zone_id') . "' AND country_id = '" . (int)$address['country_id'] . "' AND (zone_id = '" . (int)$address['zone_id'] . "' OR zone_id = '0')");

if (!$this->config->get('auspost_geo_zone_id')) {
$status = true;
} elseif ($query->num_rows) {
$status = true;
} else {
$status = false;
}

$error = '';

$quote_data = array();

if ($status) {
$weight = $this->weight->convert($this->cart->getWeight(), $this->config->get('config_weight_class_id'), $this->config->get('auspost_weight_class_id'));

if ($this->config->get('auspost_standard') && $address['iso_code_2'] == 'AU') {
$curl = curl_init();

curl_setopt($curl, CURLOPT_URL, 'http://drc.edeliver.com.au/ratecalc.asp ... _postcode=' . urlencode($this->config->get('auspost_postcode')) . '&destination_postcode=' . urlencode($address['postcode']) . '&height=70&width=70&length=70&country=AU&service_type=standard&quantity=1&weight=' . urlencode($weight));
curl_setopt($curl, CURLOPT_HEADER, 0);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);

$response = curl_exec($curl);

curl_close($curl);

if ($response) {
$response_info = array();

$parts = explode("\n", trim($response));

foreach ($parts as $part) {
list($key, $value) = explode('=', $part);

$response_info[$key] = $value;
}

if ($response_info['err_msg'] != 'OK') {
$error = $response_info['err_msg'];
} else {
$title = $this->language->get('text_standard');

if ($this->config->get('auspost_display_time')) {
//$title .= ' (' . $response_info['days'] . ' ' . $this->language->get('text_eta') . ')';
}

$quote_data['standard'] = array(
'code' => 'auspost.standard',
'title' => $title,
'cost' => $this->currency->convert($response_info['charge'], 'AUD', $this->config->get('config_currency')),
'tax_class_id' => $this->config->get('auspost_tax_class_id'),
'text' => $this->currency->format($this->tax->calculate($this->currency->convert($response_info['charge'], 'AUD', $this->currency->getCode()), $this->config->get('auspost_tax_class_id'), $this->config->get('config_tax')), $this->currency->getCode(), 1.0000000)
);
}
}
}

if ($this->config->get('auspost_express') && $address['iso_code_2'] == 'AU') {
$curl = curl_init();

curl_setopt($curl, CURLOPT_URL, 'http://drc.edeliver.com.au/ratecalc.asp ... _postcode=' . urlencode($this->config->get('auspost_postcode')) . '&destination_postcode=' . urlencode($address['postcode']) . '&height=70&width=70&length=70&country=AU&service_type=express&quantity=1&weight=' . urlencode($weight));
curl_setopt($curl, CURLOPT_HEADER, 0);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);

$response = curl_exec($curl);

curl_close($curl);

if ($response) {
$response_info = array();

$parts = explode("\n", trim($response));

foreach ($parts as $part) {
list($key, $value) = explode('=', $part);

$response_info[$key] = $value;
}

if ($response_info['err_msg'] != 'OK') {
$error = $response_info['err_msg'];
} else {
$title = $this->language->get('text_express');

if ($this->config->get('auspost_display_time')) {
$title .= ' (' . $response_info['days'] . ' ' . $this->language->get('text_eta') . ')';
}

$quote_data['express'] = array(
'code' => 'auspost.express',
'title' => $title,
'cost' => $this->currency->convert($response_info['charge'], 'AUD', $this->config->get('config_currency')),
'tax_class_id' => $this->config->get('auspost_tax_class_id'),
'text' => $this->currency->format($this->tax->calculate($this->currency->convert($response_info['charge'], 'AUD', $this->currency->getCode()), $this->config->get('auspost_tax_class_id'), $this->config->get('config_tax')), $this->currency->getCode(), 1.0000000)
);
}
}
}
}

$method_data = array();

if ($quote_data) {
$method_data = array(
'code' => 'auspost',
'title' => $this->language->get('text_title'),
'quote' => $quote_data,
'sort_order' => $this->config->get('auspost_sort_order'),
'error' => $error
);
}

return $method_data;
}
}
?>