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	$43.43	4.199%	$45.2536	$45.25	$45.25	$45.30
Purchase #2	$106.59	4.703%	$111.6029	$111.60	$111.60	$111.60
Purchase #3	$172.59	3.294%	$178.2751	$178.28	$178.30	$178.30
Purchase #4	$10.52	12.234%	$11.807	$11.81	$11.80	$11.80
Purchase #5	$210.38	9.727%	$230.8437	$230.84	$230.85	$230.80
Purchase #6	$17.86	10.822%	$19.7928	$19.79	$19.80	$19.80
Purchase #7	$111.84	13.303%	$126.7181	$126.72	$126.70	$126.70
7 purchase totals =	$673.21		$724.2932	$724.29	$724.30	$724.30