working with foreign currencies in invoicing database
i currently have an invoicing solution that was developed for use in a single currency environment. on the rare occaison that i had to create an invoice for a foreign currency, i would simply use the foreign amounts as if they were dollars, and then later after receiving payment, go back and change the amounts previously entered so that they accurately reflected how many dollars i received. this is fine for an occaisional invoice but, of course, very clumsy. if you ever need to reprint the invoice again in the foreign currency you would have had to make a note somewhere else of the amounts, and then re-enter then to print the invoice, and then change back again to dollars. i now generate more foreign currency invoices and was wondering if there was an accepted or preferred way for setting this up. for example, you could create two parallel sets of fields for unit prices, subtotals and totals (one for foreign currency and one for dollars) and have no real relationship between them and just use one for generating the client's invoice and the other (dollar) amounts for calculating sales totals and taxes. or, you could set it up with a set of fields for "nominal" prices, subtotals and totals, and then a "final" amount which would be the "nominal" amount multiplied by the conversion rate (which would be "1" for dollars) at the time of payment. and, of course i'm sure there are other ways to handle this. does anyone know what the best method is for this? any ideas would be greatly appreciated.