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	$118.42	10.298%	$130.6149	$130.61	$130.60	$130.60
Purchase #2	$247.53	3.122%	$255.2579	$255.26	$255.25	$255.30
Purchase #3	$12.98	8.385%	$14.0684	$14.07	$14.05	$14.10
Purchase #4	$136.43	10.618%	$150.9161	$150.92	$150.90	$150.90
Purchase #5	$242.28	4.776%	$253.8513	$253.85	$253.85	$253.90
Purchase #6	$174.89	5.574%	$184.6384	$184.64	$184.65	$184.60
Purchase #7	$109.62	11.732%	$122.4806	$122.48	$122.50	$122.50
7 purchase totals =	$1,042.15		$1,111.8276	$1,111.83	$1,111.80	$1,111.90