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	$190.51	3.113%	$196.4406	$196.44	$196.45	$196.40
Purchase #2	$91.33	4.675%	$95.5997	$95.60	$95.60	$95.60
Purchase #3	$53.73	3.345%	$55.5273	$55.53	$55.55	$55.50
Purchase #4	$126.95	13.296%	$143.8293	$143.83	$143.85	$143.80
Purchase #5	$176.86	11.298%	$196.8416	$196.84	$196.85	$196.80
Purchase #6	$223.92	5.733%	$236.7573	$236.76	$236.75	$236.80
Purchase #7	$212.30	6.582%	$226.2736	$226.27	$226.25	$226.30
7 purchase totals =	$1,075.60		$1,151.2694	$1,151.27	$1,151.30	$1,151.20