Fix VirtualMerchant 'ssl_salestax' errors
This error appears when your VirtualMerchant is incorrectly configured. While your store may charge taxes on orders, the amount that Shopify sends to the payment gateway to be processed isn’t broken down into subtotals/taxes, it’s just a lump sum.
To resolve it, go to Payment Field Setup, ensure that Sales Tax is set to No. Afterwards, run a test transaction to ensure everything’s running correctly.