{% set product_rating = product.rating() %}
<span style="margin-right: -4px">
  {% for i in range(1, product_rating.average_int) %}&starf;{% endfor %}
</span>
{% if product_rating.average_int != 5 %}
  {% for i in range(1, 5 - product_rating.average_int) %}&star;{% endfor %}
{% endif %}