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	$55.81	10.812%	$61.8442	$61.84	$61.85	$61.80
Purchase #2	$231.47	13.470%	$262.649	$262.65	$262.65	$262.60
Purchase #3	$208.49	8.515%	$226.2429	$226.24	$226.25	$226.20
Purchase #4	$194.67	6.724%	$207.7596	$207.76	$207.75	$207.80
Purchase #5	$48.79	6.777%	$52.0965	$52.10	$52.10	$52.10
Purchase #6	$122.91	13.675%	$139.7179	$139.72	$139.70	$139.70
Purchase #7	$100.73	10.728%	$111.5363	$111.54	$111.55	$111.50
7 purchase totals =	$962.87		$1,061.8464	$1,061.85	$1,061.85	$1,061.70