If your records include money values that might be in any currency, you might want to provide a smart way of designating that in your application and even support automatic conversions into another currency.
A simple way to do this is to use Number fields type instead of Currency with your primary object (let's say, "Orders"), and then add a new object to your application called Currencies. This object will have fields "Currency Name" and "Code", and could also include conversion values (either just one for current value, or perhaps multiple fields for historical values). Then, create a One-to-Many connection between Currencies and Orders (each Currency may be associated with many Order, but each Order is associated with only one Currency). Make the format of the connection field "Searchable Dropdown".
Now you may want to populate your Currencies object with a standard list of currencies from some web source, such as one of the providers of currency exchange rates, or Wikipedia. I did this by copying and pasting into Excel, exporting to .CSV, and then importing that into your new table. You only need the Code and Country/Currency.
Now when entering records, you can select from a list of currencies.
Once this is setup, you can also implement some advanced features, like automatic currency conversions. For example, you can add an "Exchange Value in USD" field to your Currency object, and you then update the value for a given currency to the current exchange rate. You could add an Equation field to your Orders object which calculated the value in a number field divided by the connected Exchange Value field to show the value in USD.