Let's say you buy a shirt. The shirt costs $10.00. The tax in your area is 9%.
This means that 9% of your purchase will be added to the subtotal to get the total.
9% of 10 is .9 (money speaking, its 9 cents.)
Therefore, you will add 9 cents to the total $10 for the shirt,
So now you pay $10.09 all together.
Does this make sense?
~theLocoCoco