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	$139.83	8.530%	$151.7575	$151.76	$151.75	$151.80
Purchase #2	$110.58	6.428%	$117.6881	$117.69	$117.70	$117.70
Purchase #3	$125.99	13.183%	$142.5993	$142.60	$142.60	$142.60
Purchase #4	$156.62	10.373%	$172.8662	$172.87	$172.85	$172.90
Purchase #5	$74.42	10.298%	$82.0838	$82.08	$82.10	$82.10
Purchase #6	$244.95	5.359%	$258.0769	$258.08	$258.10	$258.10
Purchase #7	$114.74	4.168%	$119.5224	$119.52	$119.50	$119.50
7 purchase totals =	$967.13		$1,044.5942	$1,044.60	$1,044.60	$1,044.70