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	$154.55	5.733%	$163.4104	$163.41	$163.40	$163.40
Purchase #2	$223.83	4.813%	$234.6029	$234.60	$234.60	$234.60
Purchase #3	$10.87	8.161%	$11.7571	$11.76	$11.75	$11.80
Purchase #4	$68.72	13.379%	$77.914	$77.91	$77.90	$77.90
Purchase #5	$217.33	12.859%	$245.2765	$245.28	$245.30	$245.30
Purchase #6	$144.41	7.677%	$155.4964	$155.50	$155.50	$155.50
Purchase #7	$121.46	5.244%	$127.8294	$127.83	$127.85	$127.80
7 purchase totals =	$941.17		$1,016.2867	$1,016.29	$1,016.30	$1,016.30