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	$134.26	5.682%	$141.8887	$141.89	$141.90	$141.90
Purchase #2	$176.54	13.382%	$200.1646	$200.16	$200.15	$200.20
Purchase #3	$6.26	9.145%	$6.8325	$6.83	$6.85	$6.80
Purchase #4	$152.90	5.570%	$161.4165	$161.42	$161.40	$161.40
Purchase #5	$173.81	3.518%	$179.9246	$179.92	$179.90	$179.90
Purchase #6	$157.43	9.232%	$171.9639	$171.96	$171.95	$172.00
Purchase #7	$150.47	6.725%	$160.5891	$160.59	$160.60	$160.60
7 purchase totals =	$951.67		$1,022.7799	$1,022.77	$1,022.75	$1,022.80