====================================================
Explanation:
15+35.50 = 50.50 dollars is the total before tax is applied.
Take 8.25% of this to get
0.0825*50.50 = 4.16625
and this rounds to 4.17, which is the amount of sales tax charged.
$4.17 = 4 dollars + 17 cents
---------
Extra info:
The grand total will be 50.50+4.17 = 54.67
Another way to get the grand total is to multiply 1.0825 by the previous subtotal (50.50) getting 50.50*1.0825 = 54.66625 and that rounds to 54.67
The multiplier 1.0825 effectively means "increase by 8.25%"
