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	$221.83	7.224%	$237.855	$237.86	$237.85	$237.90
Purchase #2	$17.41	9.123%	$18.9983	$19.00	$19.00	$19.00
Purchase #3	$90.95	10.760%	$100.7362	$100.74	$100.75	$100.70
Purchase #4	$138.82	3.222%	$143.2928	$143.29	$143.30	$143.30
Purchase #5	$102.44	13.615%	$116.3872	$116.39	$116.40	$116.40
Purchase #6	$122.29	8.325%	$132.4706	$132.47	$132.45	$132.50
Purchase #7	$11.28	4.713%	$11.8116	$11.81	$11.80	$11.80
7 purchase totals =	$705.02		$761.5517	$761.56	$761.55	$761.60