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	$151.70	4.723%	$158.8648	$158.86	$158.85	$158.90
Purchase #2	$8.50	3.148%	$8.7676	$8.77	$8.75	$8.80
Purchase #3	$40.51	3.260%	$41.8306	$41.83	$41.85	$41.80
Purchase #4	$145.33	8.127%	$157.141	$157.14	$157.15	$157.10
Purchase #5	$49.29	6.712%	$52.5983	$52.60	$52.60	$52.60
Purchase #6	$162.51	12.208%	$182.3492	$182.35	$182.35	$182.30
Purchase #7	$70.68	11.152%	$78.5622	$78.56	$78.55	$78.60
7 purchase totals =	$628.52		$680.1137	$680.11	$680.10	$680.10