Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$193.87	3.536%	$200.7252	$200.73	$200.75	$200.70
Purchase #2	$192.82	10.714%	$213.4787	$213.48	$213.50	$213.50
Purchase #3	$91.34	4.564%	$95.5088	$95.51	$95.50	$95.50
Purchase #4	$139.34	12.285%	$156.4579	$156.46	$156.45	$156.50
Purchase #5	$145.48	4.565%	$152.1212	$152.12	$152.10	$152.10
Purchase #6	$224.85	7.468%	$241.6418	$241.64	$241.65	$241.60
Purchase #7	$198.25	8.630%	$215.359	$215.36	$215.35	$215.40
7 purchase totals =	$1,185.95		$1,275.2926	$1,275.30	$1,275.30	$1,275.30