With osCommerce you can also set up the sales taxes for certain regions of countries or states. That can be done in the Locations / Taxes section of the administrative interface.
To change the languages and currencies, you will need to visit the Localization section.
Currencies in osCommerce
The currencies that are included in the standard installation will be listed, with US Dollar being the default one.
You can add other currencies as well, according to your preference. Click on the New Currency button to proceed.
Please note that in case you are having more than one currency, you will need to specify values for the additional ones, relative to the default one (the default currency value should become 1, and all other have values relative to it in order to have the prices calculated correctly).
Languages in osCommerce
New languages can be downloaded from the address below:
The language packs include instructions on how to set up the new language. The procedure can be started from Localization -> Languages -> New Language.