From In-Portal User Manual

Currencies

This section lists all currencies supported by In-commerce in the current version. All currencies are listed by their ISO code (the same code that is used by all of the banks). While it is not possible to add currencies to this list for the administrator, it is the most complete list that was available to us at the time of the current release, and we are going to update it with each new release. At this time there are 177 currencies supported by In-commerce.
The administrator can modify the settings and parameters for each currency. In-commerce requires one primary currency to be enabled at all times, and there is no limitation to how many currencies can be enabled.
The primary currency is used for all calculations, and is assumed the currency of all prices entered through the Administrative Console. This applies, for example, to product price brackets, discount amounts, order totals, etc. When an order is placed in a different currency, In-commerce uses the exchange rate, specified in this section, to convert all of the amounts from the primary currency. By default, the primary currency in In-commerce is U.S. dollar.
The toolbar action icons are as follows:

• Edit – modifies the properties of the selected currencies.
• Set Primary – designates the primary currency. The previously chosen primary currency is automatically unselected, as there can be only one primary currency in the system. You cannot disable the primary currency, and if you designate a disabled currency as primary, it will automatically become enabled.
• Approve – enables the selected currencies. Only enabled currencies are visible on the storefront, and only enabled currencies can be used in orders, both on the storefront and in the Administrative Console.
• Decline – disables the selected currencies.
• Priority Up, Priority Down – as with many other In-portal items, the sorting of the currencies can be adjusted by the priority. Currencies within the same priority are sorted by their ISO code on the storefront.
• Update Rates – automatically updates the rates of the selected currencies. This is the most important operation concerning the currencies. For any international store accepting more than one currency, we strongly advise to update the currencies at least once per day. When you hit the Update Rates button, In-commerce connects to the online bank of your choice (set in the General Settings section, read more about it in manual), and requests an update for the exchange rate of the selected currencies. Please note that the rate information comes directly from the selected bank, and In-commerce does not alter or validate it in any way. If the information for one or more currencies is not available at that time, or if the connection to the bank cannot be made, no update is performed. If no currency is selected when pressing this button, the system will attempt to update the rate for all enabled currencies. You can get a quick indication of whether the update was successful by reviewing the Last Updated column, which shows the date and time of the last modification of the currency.