Can we apply tax percentage on each item separately?

Hello, usama. 

Yes, you can. However, I would create a bundle item that includes your product or service that is considered taxable along with the sales tax item. This would allow you to make the sales tax amount variable.
 

You need to ensure the inventory is turned on. Go to the Gear icon > Company settings > Sales > Products and Services.

You’ll see Bundles as a new option when you go to add an item to the Products and Services list.

For more information, read my blog on recent Inventory updates.

Please leave a comment down below if you have other queries with the process. I'll be glad to help as soon as I can. Keep safe and healthy always.