# add following to mysite/myapp/templatetags/myapp_tags.py

from django import template
register = template.Library()

@register.filter
def mod(value, arg):
    return value % arg


#put following in your template and change mod:5
#according to the number of cells per table row desired

{% load pictures_tags %}

<table>
<tr>
{% for item in list %}
  <td>
  <!--CELL CONTENT-->
  </td>
  {% if not forloop.counter|mod:5 %}
    </tr><tr>
  {% endif %}
{% endfor %}
</tr>
</table>