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	$62.46	6.325%	$66.4106	$66.41	$66.40	$66.40
Purchase #2	$151.91	3.348%	$156.9959	$157.00	$157.00	$157.00
Purchase #3	$224.48	9.627%	$246.0907	$246.09	$246.10	$246.10
Purchase #4	$249.72	4.596%	$261.1971	$261.20	$261.20	$261.20
Purchase #5	$25.27	7.359%	$27.1296	$27.13	$27.15	$27.10
Purchase #6	$85.94	4.554%	$89.8537	$89.85	$89.85	$89.90
Purchase #7	$161.51	8.109%	$174.6068	$174.61	$174.60	$174.60
7 purchase totals =	$961.29		$1,022.2844	$1,022.29	$1,022.30	$1,022.30