It's easy to determine the difference between inclusive tax and exclusive tax. It all depends on whether the tax is added on top of the total retail price, or not.
Inclusive tax - The taxes are already a part of the product's retail price, so no more taxes are added to the subtotal of the sales transaction.
Exclusive tax - The taxes are not yet a part of the retail price, so the tax amount is added to the subtotal of the sales transaction, before the checkout is finalized.
So how do you set it up? First, go to the Manage Taxes section in Settings > Store. Once you turn it on, you should see an option that says Include tax in retail price.
If the Include tax in retail price option is checked, then your tax is set as inclusive.
But if your leave the Include tax in retail price option to remain with a check, then your tax is set as exclusive.