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	$141.85	10.644%	$156.9485	$156.95	$156.95	$156.90
Purchase #2	$75.51	13.390%	$85.6208	$85.62	$85.60	$85.60
Purchase #3	$136.44	13.183%	$154.4269	$154.43	$154.45	$154.40
Purchase #4	$115.58	9.138%	$126.1417	$126.14	$126.15	$126.10
Purchase #5	$205.84	3.333%	$212.7006	$212.70	$212.70	$212.70
Purchase #6	$105.54	5.792%	$111.6529	$111.65	$111.65	$111.70
Purchase #7	$93.76	12.555%	$105.5316	$105.53	$105.55	$105.50
7 purchase totals =	$874.52		$953.0230	$953.02	$953.05	$952.90