@incitrio You may be in luck. While the HubSpot’s only way (until now) to have automated sales tax calculation has been through Stripe/TaxJar, my company just built an integration that connects HubSpot to Avalara so companies can leverage AvaTax for the tax calculation. The app is in the HubSpot Marketplace and is called ‘Sales Tax powered by AvaTax’.
In your case, your client could have both HubSpot and Infor connected to AvaTax. Other folks I’ve seen using similar setups are usually sending the Quote out of HubSpot and then finalizing the transaction out of the ERP. But either way, with both HubSpot and Infor connected, they could select which system commits the information to Avalara.