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	$10.64	9.296%	$11.6291	$11.63	$11.65	$11.60
Purchase #2	$142.94	5.790%	$151.2162	$151.22	$151.20	$151.20
Purchase #3	$100.81	10.118%	$111.01	$111.01	$111.00	$111.00
Purchase #4	$79.77	11.465%	$88.9156	$88.92	$88.90	$88.90
Purchase #5	$61.25	3.814%	$63.5861	$63.59	$63.60	$63.60
Purchase #6	$64.70	4.160%	$67.3915	$67.39	$67.40	$67.40
Purchase #7	$223.58	3.133%	$230.5848	$230.58	$230.60	$230.60
7 purchase totals =	$683.69		$724.3333	$724.34	$724.35	$724.30