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	$186.55	4.597%	$195.1257	$195.13	$195.15	$195.10
Purchase #2	$106.29	5.197%	$111.8139	$111.81	$111.80	$111.80
Purchase #3	$139.58	12.135%	$156.518	$156.52	$156.50	$156.50
Purchase #4	$243.94	13.470%	$276.7987	$276.80	$276.80	$276.80
Purchase #5	$141.69	3.459%	$146.5911	$146.59	$146.60	$146.60
Purchase #6	$171.95	6.861%	$183.7475	$183.75	$183.75	$183.70
Purchase #7	$115.81	8.684%	$125.8669	$125.87	$125.85	$125.90
7 purchase totals =	$1,105.81		$1,196.4618	$1,196.47	$1,196.45	$1,196.40