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	$183.48	7.274%	$196.8263	$196.83	$196.85	$196.80
Purchase #2	$137.51	11.198%	$152.9084	$152.91	$152.90	$152.90
Purchase #3	$214.68	4.547%	$224.4415	$224.44	$224.45	$224.40
Purchase #4	$30.64	10.416%	$33.8315	$33.83	$33.85	$33.80
Purchase #5	$117.28	11.429%	$130.6839	$130.68	$130.70	$130.70
Purchase #6	$94.48	11.367%	$105.2195	$105.22	$105.20	$105.20
Purchase #7	$208.55	11.146%	$231.795	$231.80	$231.80	$231.80
7 purchase totals =	$986.62		$1,075.7061	$1,075.71	$1,075.75	$1,075.60