Does the TaxJar API convert currency?

No, the TaxJar API does not convert your currency values. 

The sales tax calculations are simply a percentage of the value you send in; it is essentially currency agnostic. 

• For example, if you collect from a customer in USD but they are in the EU and you are calculating VAT, we do not do any conversion from USD to EUR.
• It's up to decide how you want to handle this if conversion is needed.For this example, you might decide to collect in EUR instead by doing the conversion on your end, and then send that converted value to the API for sales tax calculation instead.

Another thing to keep in mind here is that all Transaction amounts in TaxJar are listed in USD, and we have more information on that here.