Look into two sections:

` app\design\frontend\base\default\template\tax\checkout\ `

` app\design\frontend\base\default\template\checkout\total\ `

Depending on your setup in tax configuration you have to manually add ':' after something like: ` <?php echo $this->getTotal()->getTitle() ? ` in:  ` app\design\frontend\base\default\template\checkout\total\tax.phtml ` 

or something like:
`<?php echo $this->escapeHtml($this->getTotal()->getTitle()); ?> ` in:  ` app\design\frontend\base\default\template\checkout\total\default.phtml `
<br><br>So you can edit it into something like this:

    <?php echo $this->escapeHtml($this->getTotal()->getTitle()) . ': '; ?>

or:

    <?php echo $this->escapeHtml($this->getTotal()->getTitle()); ?>: