userCurrency

This contrib does a few things related to currency management:
1) When a guest (non logged in user) visits, their IP is checked against a database to determine country. This is cross-referenced with a table of currencies for each country. Provided that currency is defined in your Localization-_Currencies section of your Admin page, the currency will be pre-selected for the customer. Otherwise your default currency will be used. The customer may choose a different currency (provided you give them that ability) and it will be remembered as expected for the rest of the session. This feature is optional (see installation and notes).
2) When a user first creates an account, the address s/he chooses is used to determine the customer's preferred currency. If the country they choose does not have a matching currency, or if that currency is not defined in your Localization-_Currencies section, the default currency will be stored.
3) Whenever a user selects a currency, that value is stored in the customers table so that it will be remembered from session to session (whenever logged in, otherwise treated as guest). Without this contrib, a customer will always revert back to the default currency which can be very confusing if currencies are similar (Canadian $ vs. American $ for example).