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	$244.27	12.562%	$274.9552	$274.96	$274.95	$275.00
Purchase #2	$189.78	5.434%	$200.0926	$200.09	$200.10	$200.10
Purchase #3	$9.55	12.282%	$10.7229	$10.72	$10.70	$10.70
Purchase #4	$239.71	10.316%	$264.4385	$264.44	$264.45	$264.40
Purchase #5	$87.74	8.348%	$95.0645	$95.06	$95.05	$95.10
Purchase #6	$102.83	3.556%	$106.4866	$106.49	$106.50	$106.50
Purchase #7	$105.29	6.254%	$111.8748	$111.87	$111.85	$111.90
7 purchase totals =	$979.17		$1,063.6351	$1,063.63	$1,063.60	$1,063.70