Create Sale Bill.
There is an Other Item Details option in the bill. Hit space bar as below:
Fig 1. Sale Bill
A new window will appear on your screen. You can see that GST Type, Sales Tax A/c and Tax 2 A/c is automatically selected in the Sale bill. See window below:
Fig 2. Sale Bill
GST Type field should reflect tax type. In case, the tax is not displaying in this box, you might have done some mistake while defining it.
Click on OK button.