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	$174.95	8.666%	$190.1112	$190.11	$190.10	$190.10
Purchase #2	$208.49	12.702%	$234.9724	$234.97	$234.95	$235.00
Purchase #3	$214.60	4.200%	$223.6132	$223.61	$223.60	$223.60
Purchase #4	$159.52	10.581%	$176.3988	$176.40	$176.40	$176.40
Purchase #5	$45.83	5.605%	$48.3988	$48.40	$48.40	$48.40
Purchase #6	$43.58	4.466%	$45.5263	$45.53	$45.55	$45.50
Purchase #7	$142.30	9.462%	$155.7644	$155.76	$155.75	$155.80
7 purchase totals =	$989.27		$1,074.7851	$1,074.78	$1,074.75	$1,074.80