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	$196.83	13.747%	$223.8882	$223.89	$223.90	$223.90
Purchase #2	$6.39	3.487%	$6.6128	$6.61	$6.60	$6.60
Purchase #3	$194.80	11.341%	$216.8923	$216.89	$216.90	$216.90
Purchase #4	$171.76	7.343%	$184.3723	$184.37	$184.35	$184.40
Purchase #5	$214.74	12.492%	$241.5653	$241.57	$241.55	$241.60
Purchase #6	$114.62	10.571%	$126.7365	$126.74	$126.75	$126.70
Purchase #7	$145.51	4.855%	$152.5745	$152.57	$152.55	$152.60
7 purchase totals =	$1,044.65		$1,152.6419	$1,152.64	$1,152.60	$1,152.70