Adding a cart icon with number of items and total cost in nav menu when using WooCommerce. http://sridharkatakam.com/adding-cart-icon-number-items-total-cost-nav-menu-using-woocommerce/

functions.php

//* Make Font Awesome available
add_action( 'wp_enqueue_scripts', 'enqueue_font_awesome' );
function enqueue_font_awesome() {

	wp_enqueue_style( 'font-awesome', '//maxcdn.bootstrapcdn.com/font-awesome/4.2.0/css/font-awesome.min.css' );

}

/**
 * Place a cart icon with number of items and total cost in the menu bar.
 *
 * Source: http://wordpress.org/plugins/woocommerce-menu-bar-cart/
 */
add_filter('wp_nav_menu_items','sk_wcmenucart', 10, 2);
function sk_wcmenucart($menu, $args) {

	// Check if WooCommerce is active and add a new item to a menu assigned to Primary Navigation Menu location
	if ( !in_array( 'woocommerce/woocommerce.php', apply_filters( 'active_plugins', get_option( 'active_plugins' ) ) ) || 'primary' !== $args->theme_location )
		return $menu;

	ob_start();
		global $woocommerce;
		$viewing_cart = __('View your shopping cart', 'your-theme-slug');
		$start_shopping = __('Start shopping', 'your-theme-slug');
		$cart_url = $woocommerce->cart->get_cart_url();
		$shop_page_url = get_permalink( wc_get_page_id( 'shop' ) );
		$cart_contents_count = $woocommerce->cart->cart_contents_count;
		$cart_contents = sprintf(_n('%d item', '%d items', $cart_contents_count, 'your-theme-slug'), $cart_contents_count);
		$cart_total = $woocommerce->cart->get_cart_total();
		// Uncomment the line below to hide nav menu cart item when there are no items in the cart
		// if ( $cart_contents_count > 0 ) {
			if ($cart_contents_count == 0) {
				$menu_item = '<li class="right"><a class="wcmenucart-contents" href="'. $shop_page_url .'" title="'. $start_shopping .'">';
			} else {
				$menu_item = '<li class="right"><a class="wcmenucart-contents" href="'. $cart_url .'" title="'. $viewing_cart .'">';
			}

			$menu_item .= '<i class="fa fa-shopping-cart"></i> ';

			$menu_item .= $cart_contents.' - '. $cart_total;
			$menu_item .= '</a></li>';
		// Uncomment the line below to hide nav menu cart item when there are no items in the cart
		// }
		echo $menu_item;
	$social = ob_get_clean();
	return $menu . $social;

}