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	$126.50	12.278%	$142.0317	$142.03	$142.05	$142.00
Purchase #2	$241.41	5.559%	$254.83	$254.83	$254.85	$254.80
Purchase #3	$104.98	5.830%	$111.1003	$111.10	$111.10	$111.10
Purchase #4	$136.27	13.266%	$154.3476	$154.35	$154.35	$154.30
Purchase #5	$58.78	4.102%	$61.1912	$61.19	$61.20	$61.20
Purchase #6	$187.39	4.365%	$195.5696	$195.57	$195.55	$195.60
Purchase #7	$77.95	11.446%	$86.8722	$86.87	$86.85	$86.90
7 purchase totals =	$933.28		$1,005.9426	$1,005.94	$1,005.95	$1,005.90