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	$57.47	7.483%	$61.7705	$61.77	$61.75	$61.80
Purchase #2	$49.63	4.145%	$51.6872	$51.69	$51.70	$51.70
Purchase #3	$131.70	5.667%	$139.1634	$139.16	$139.15	$139.20
Purchase #4	$183.38	7.222%	$196.6237	$196.62	$196.60	$196.60
Purchase #5	$212.66	5.170%	$223.6545	$223.65	$223.65	$223.70
Purchase #6	$148.53	5.767%	$157.0957	$157.10	$157.10	$157.10
Purchase #7	$231.88	5.754%	$245.2224	$245.22	$245.20	$245.20
7 purchase totals =	$1,015.25		$1,075.2174	$1,075.21	$1,075.15	$1,075.30