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	$92.56	3.252%	$95.5701	$95.57	$95.55	$95.60
Purchase #2	$185.74	13.327%	$210.4936	$210.49	$210.50	$210.50
Purchase #3	$132.87	4.795%	$139.2411	$139.24	$139.25	$139.20
Purchase #4	$131.70	5.602%	$139.0778	$139.08	$139.10	$139.10
Purchase #5	$111.76	10.695%	$123.7127	$123.71	$123.70	$123.70
Purchase #6	$113.41	11.737%	$126.7209	$126.72	$126.70	$126.70
Purchase #7	$160.30	4.139%	$166.9348	$166.93	$166.95	$166.90
7 purchase totals =	$928.34		$1,001.7510	$1,001.74	$1,001.75	$1,001.70