To display the Domestic Tax in the Product Detail page go to Design and select Themes.
Next, select the theme that you need to
edit. Once you are in the Theme, look in the left section under General
Settings and find Product Detail as shown below.
Click on the title and the Product Detail settings will unfold with the Show Domestic Tax option displayed as
shown below. Tick the Show Domestic Tax check box and
lastly, click Save Themes Settings.