ConnectWise Manage 2017.5 has introduced the ability to change the Currency on an Invoice. 
Multi-Currency Invoice Sync management is available on the Sync-Ninja plans. 

If this feature has been turned on, you have the ability to sync an invoice in a currency which is not the Billing Location set currency.

Known Issue:
Currency within ConnectWise is a label and there is no conversion tool available within ConnectWise. This means that an invoice can be generated as a $