To ensure you are able to apply tax while checking out a guest, you can simply set up the tax percentage based on your country (Currently only supporting United States and India).
Simply go to My Account and click on 'Marketplace'
Then click on 'Tax Setup'
Based on your country, you will get an option to set a tax percentage that can be applied at checkout.
For example,
Here, I've setup the tax percentage to 9.50%
Now if I try to checkout a guest, sales tax will be automatically applied:
For India, you will have the option to setup
CGST, SGST, and VAT
CGST and SGST will apply at checkout automatically if set up by the admin but please note, you will manually have to turn the toggle on for VAT under 'Other Charges' and hit 'Apply' for it to be applied.
VAT is not applicable on all items so it does not apply automatically. 