THEMENAME_menu_link.php

<?php
function THEMENAME_menu_link(array $variables) {
	$element = $variables['element'];
	$sub_menu = '';
	
	if ($element['#below']) {
	  $sub_menu = drupal_render($element['#below']);
	}
	
	if (empty($element['#localized_options'])) {
	  $element['#localized_options'] = array();
	}
	
	/* Changes URL to current page and adds the anchor name #top to the end based on menu title "Jump to Top"*/
	if (($element['#title']) == "Jump to Top") {
	  $current_url = "http://" .$_SERVER['HTTP_HOST'] . request_uri(); 
	  $output = l($element['#title'], $current_url , array('fragment' => "top"));
	}
	else {
		$output = l($element['#title'], $element['#href'], $element['#localized_options']);
	}
	
	return '<li' . drupal_attributes($element['#attributes']) . '>' . $output . $sub_menu . "</li>\n";
}
?>