Override price.php file - woocommerce - price do not returns decimal zero - put this script in "your-theme/woocommerce/loop/price.php"

price.php

<?php
/**
 * Loop Price
 * Overriding original price.php
 * @author 	Marcos Freitas - WooThemes
 * @package 	WooCommerce/Templates
 * @version     1.6.4
 */

if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

global $product;

/**
 * Deixei a verificação original
 * o price_html não estava retornando as casas decimais quando elas eram zeros
 */

    if ( $price_html = $product->get_price_html() ) :
        
        $currency = get_woocommerce_currency_symbol(); // pega o símbolo da moeda
        $price_value = number_format($product->price, 2, ',', '.'); // formata o valor para o padrão BR
?>
<div class="price"><span class="amount"><?php echo $currency.' '.$price_value;?> </span></div>
<?php
    endif;
?>