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	$87.64	8.116%	$94.7529	$94.75	$94.75	$94.80
Purchase #2	$149.67	7.532%	$160.9431	$160.94	$160.95	$160.90
Purchase #3	$222.94	7.145%	$238.8691	$238.87	$238.85	$238.90
Purchase #4	$81.55	4.430%	$85.1627	$85.16	$85.15	$85.20
Purchase #5	$58.65	13.706%	$66.6886	$66.69	$66.70	$66.70
Purchase #6	$248.63	8.657%	$270.1539	$270.15	$270.15	$270.20
Purchase #7	$225.74	13.167%	$255.4632	$255.46	$255.45	$255.50
7 purchase totals =	$1,074.82		$1,172.0335	$1,172.02	$1,172.00	$1,172.20