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	$60.89	10.397%	$67.2207	$67.22	$67.20	$67.20
Purchase #2	$110.92	11.537%	$123.7168	$123.72	$123.70	$123.70
Purchase #3	$167.42	8.590%	$181.8014	$181.80	$181.80	$181.80
Purchase #4	$220.36	9.637%	$241.5961	$241.60	$241.60	$241.60
Purchase #5	$151.69	4.491%	$158.5024	$158.50	$158.50	$158.50
Purchase #6	$204.93	6.325%	$217.8918	$217.89	$217.90	$217.90
Purchase #7	$146.62	6.523%	$156.184	$156.18	$156.20	$156.20
7 purchase totals =	$1,062.83		$1,146.9132	$1,146.91	$1,146.90	$1,146.90