Display zero shipping fee

This can be achieved by editing

app/code/core/Mage/Sales/etc/config.xml

replace

<shipping translate="title">
    <title>Shipping & Handling</title>
    <source_field>shipping_amount</source_field>
    <font_size>7</font_size>
    <display_zero>0</display_zero>
    <sort_order>400</sort_order>
</shipping>

with

<shipping translate="title">
    <title>Shipping & Handling</title>
    <source_field>shipping_amount</source_field>
    <font_size>7</font_size>
    <display_zero>1</display_zero>
    <sort_order>400</sort_order>
</shipping>