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	$53.57	11.468%	$59.7134	$59.71	$59.70	$59.70
Purchase #2	$218.54	9.636%	$239.5985	$239.60	$239.60	$239.60
Purchase #3	$171.29	3.597%	$177.4513	$177.45	$177.45	$177.50
Purchase #4	$223.65	13.273%	$253.3351	$253.34	$253.35	$253.30
Purchase #5	$210.55	13.825%	$239.6585	$239.66	$239.65	$239.70
Purchase #6	$28.38	3.809%	$29.461	$29.46	$29.45	$29.50
Purchase #7	$165.41	4.549%	$172.9345	$172.93	$172.95	$172.90
7 purchase totals =	$1,071.39		$1,172.1523	$1,172.15	$1,172.15	$1,172.20