We can't see your server paths from the outside, but my best guess would be that you should set the first line to
PHP Code:
DEFINE('PATH_TO_STORE_ROOT','');
and set the next two back to
PHP Code:
// Get Zen Cart configuration data
require_once(PATH_TO_STORE_ROOT . 'includes/configure.php');
require_once(PATH_TO_STORE_ROOT . 'includes/database_tables.php');
This is based on a reading of your warning and error messages that seem to suggest that you have placed the currency update file in your site's root folder
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