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	$127.33	13.836%	$144.9474	$144.95	$144.95	$144.90
Purchase #2	$143.39	8.618%	$155.7474	$155.75	$155.75	$155.70
Purchase #3	$30.55	10.871%	$33.8711	$33.87	$33.85	$33.90
Purchase #4	$118.38	5.468%	$124.853	$124.85	$124.85	$124.90
Purchase #5	$165.87	5.208%	$174.5085	$174.51	$174.50	$174.50
Purchase #6	$172.67	11.490%	$192.5098	$192.51	$192.50	$192.50
Purchase #7	$230.45	7.445%	$247.607	$247.61	$247.60	$247.60
7 purchase totals =	$988.64		$1,074.0442	$1,074.05	$1,074.00	$1,074.00