Update app/code/core/Mage/Adminhtml/Block/Catalog/Product/Helper/Form/Price.php

Recently had an issue where the price of a product had 3 decimal points on the DB, 10.245 for example, but showed the rounded to 2 decimals price (10.25) on the admin panel product edit page.

When hitting save for that product from the admin panel, it would save the escaped value with 2 decimal points, replacing 10.245 with 10.25, which is completely undesirable and results in all kind of funny prices after taxes are applied.

Possible fixes: 
(1) Allow more decimal points. 4 seems reasonable, but the issue might persist.
(2) Simply return $value as it comes from the database, since the method already checks that is a numeric value.

Note: the other reason why the number_format was being done is to remove the thousand comma separator, but is_numeric(1,230) is false, so price data coming from the DB with comma thousand separators won't be valid anyway.