B2BKing setting WooCommerce Customer Role

When customers register as B2B customers, one feature they all need is to be able to enter their tax exempt certificate number and have sales tax not charged.  We have a tax plugin that does that.  The problem is that when they register with B2Bking, they always get the default "customer" role.  We have a role specifically for B2B customers called "Exempt Customers" which the tax plugin looks for and presents an option to add their tax certificate to the database on the first use.  After that, they can update the number if necessary, or simply select the one in the DB.  

So my question is this, is there some parameter on the registration short codes ( or the possibility of adding one) to force the customer role for WooCommerce to be what we want--in our case "Exempt Customer"?

Thanks,

Greg Guldenschuh