As @QMcKay suggested.
Create 2 tax accounts. I setup Account Types as Sales Accounts. You can create separate Account Type (like Tax Accounts) if you need.
Create 2 Account Transaction Types for each Tax Accounts.
Both should appear fine here.
Create a Tax Template for permanent GST.
Map it to all products.
Create another tax template for %8 Tax. I named it as PTAX.
Create a new action to apply both Taxes to orders.
Create another one to apply only %5 tax.
Create a rule for %13 tax.
Create another for %5
Here we go.
When ticket total is $3.00 tax amount is $0.15 (%5). When I add more orders and make ticket total $6.00 tax becomes $0.78 (%13).
PS: While implementing this I noticed it does not work as expected when we gift an item as action works only for selected orders. There are ways to solve that but for next update (.61) I added a parameter to ignore selected orders and apply order updates to all orders.