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	$246.42	3.331%	$254.6283	$254.63	$254.65	$254.60
Purchase #2	$32.29	6.175%	$34.2839	$34.28	$34.30	$34.30
Purchase #3	$221.78	7.189%	$237.7238	$237.72	$237.70	$237.70
Purchase #4	$79.82	12.852%	$90.0785	$90.08	$90.10	$90.10
Purchase #5	$244.85	4.761%	$256.5073	$256.51	$256.50	$256.50
Purchase #6	$92.84	3.250%	$95.8573	$95.86	$95.85	$95.90
Purchase #7	$41.71	8.137%	$45.1039	$45.10	$45.10	$45.10
7 purchase totals =	$959.71		$1,014.1830	$1,014.18	$1,014.20	$1,014.20