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	$84.84	3.564%	$87.8637	$87.86	$87.85	$87.90
Purchase #2	$246.41	3.732%	$255.606	$255.61	$255.60	$255.60
Purchase #3	$91.57	9.869%	$100.607	$100.61	$100.60	$100.60
Purchase #4	$175.48	13.491%	$199.154	$199.15	$199.15	$199.20
Purchase #5	$158.79	6.354%	$168.8795	$168.88	$168.90	$168.90
Purchase #6	$231.33	10.776%	$256.2581	$256.26	$256.25	$256.30
Purchase #7	$74.75	13.466%	$84.8158	$84.82	$84.80	$84.80
7 purchase totals =	$1,063.17		$1,153.1841	$1,153.19	$1,153.15	$1,153.30