Sorry, but I have'nt expertise on Taxjar, but on Quaderno I've done a integration using their API.
For known about what taxes we must to apply based on from comes the customer. And to made invoices, credits and receipts.
Due to our needs we don't use subscription system from Quaderno, first because when we started with they that service do'nt exists yet, and second because we need to invoice a different ammount on every invoice based on which plan and consume are done by every customer.
They are kind, responds fast to queries, and their API are simple but powerful. We use webhooks to register all the changes from the invoices, contacts (customers), and all the other documents.
You can see their API and SDKs on https://github.com/quaderno
Good luck.
