In Zoho Books, the item prices will always be in the base currency.
To invoice a customer with a foreign currency, you first need to associate that currency to your customer. This will be applied when you raise an invoice for that particular customer and the item price in your base currency will be converted to your customer’s currency based on the exchange rate you provide.
Note: Only one currency can be associated to a contact
To associate a currency to your customer:
To enter the exchange rate for your customer’s currency:
Note: Please note that if you already have transactions for your customer in your base currency, you won’t able change the currency. To resolve this problem, you have to delete all the transactions which are associated with the customer.