Question: I have been struggling immensely to change the label of "Subtotal" in the email sent to users after they make a purchase.

I was able to remove everything BUT the sub total column, and I want to replace sub total with "Grand Total". I tried modifying the `Mage_Sales.csv` in `app/locale/en_US`, to no avail.

Does anyone have an idea on how or where I can change this?

I have a hunch it is in an .xml file, but I honestly don't know.

This image shows what I want changed as well. Thanks!

<http://img836.imageshack.us/img836/3865/fe1v.png>

Answer: 
I found the answer, thanks to Sander's example of Grep. I grepped for `"('Subtotal')"` and in `/app/code/core/Mage/Sales/Block/Order/Totals.php` I modified this section, around line 90.

```
    /**
     * Initialize order totals array
     *
     * @return Mage_Sales_Block_Order_Totals
     */
    protected function _initTotals()
    {
        $source = $this->getSource();

        $this->_totals = array();
        $this->_totals['subtotal'] = new Varien_Object(array(
            'code'  => 'subtotal',
            'value' => $source->getSubtotal(),
            'label' => $this->__('Subtotal')
        ));

```

I must have messed up somewhere, because I am sure one of the `.csv`'s Sander had listed in the locale must have related to this piece. Since my shop does not need to upgrade and does not need other languages, I went ahead and wrote "Grand Total" in directly. For others who may see this, I recommend, as everyone else has, to modify a locale instead.

Thanks Sander and everyone else who has helped!
There is `"Subtotal"` and `"Subtotal:"` in `en_US/Mage_Sales.csv`. Are you sure you modified the one w/o colon? Also the Magento cache had to be flushed afterwards.

P.S. This is not the prettiest way to modify the translation instance as it will be overwritten with the next Magento version which is suppose to come in the end of September.