The currency converter included in Out of the Sandbox themes will change the price displayed to customers based on their selection, once the checkout process begins, prices will revert back to your store's default currency.
Please note: the theme's built-in currency converter does not support the ability to automatically detect a user's location and change the currency to the appropriate local one.
However, support for Shopify Payment's native multi-currency feature has been added to recent updates of our themes. This feature lets you configure native multi-currencies to allow customers to checkout in their selected currency. Learn more about using Shopify Payment's Multi-Currency feature
To enable the currency converter:
Head into Online Store > Themes > Customize > Theme settings > Currency Converter.
Then in the next fields, you can choose which currencies you want to offer, your default currency and if you want to display the currency code after the price, such as (with currency) "$10.00 USD" or (without currency) "$10.00".
You can find a list of all of the currencies that are supported here and Shopify's documentation on store currency can be found here.