If you have an item that costs 10 dollars and a sales tax of 7% you could do it this way
10 * 7/100 = 0.70 dollars.
The total cost is 10.70 dollars. or 10 dollars and 70 cents.
The best way to do the total however is to multiply the cost by 1.07. You will get the number the customer has to pay.
10 * 1.07 = 10.70
So for any price (p) it would be 1.07*p
