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	$152.82	5.104%	$160.6199	$160.62	$160.60	$160.60
Purchase #2	$212.64	7.597%	$228.7943	$228.79	$228.80	$228.80
Purchase #3	$214.62	4.684%	$224.6728	$224.67	$224.65	$224.70
Purchase #4	$52.31	5.439%	$55.1551	$55.16	$55.15	$55.20
Purchase #5	$157.89	9.109%	$172.2722	$172.27	$172.25	$172.30
Purchase #6	$59.80	3.140%	$61.6777	$61.68	$61.70	$61.70
Purchase #7	$136.85	13.488%	$155.3083	$155.31	$155.30	$155.30
7 purchase totals =	$986.93		$1,058.5003	$1,058.50	$1,058.45	$1,058.60