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	$214.60	6.157%	$227.8129	$227.81	$227.80	$227.80
Purchase #2	$155.87	5.872%	$165.0227	$165.02	$165.00	$165.00
Purchase #3	$145.49	13.789%	$165.5516	$165.55	$165.55	$165.60
Purchase #4	$143.66	12.693%	$161.8948	$161.89	$161.90	$161.90
Purchase #5	$108.79	5.482%	$114.7539	$114.75	$114.75	$114.80
Purchase #6	$157.51	10.816%	$174.5463	$174.55	$174.55	$174.50
Purchase #7	$68.58	5.286%	$72.2051	$72.21	$72.20	$72.20
7 purchase totals =	$994.50		$1,081.7873	$1,081.78	$1,081.75	$1,081.80