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	$100.88	13.292%	$114.289	$114.29	$114.30	$114.30
Purchase #2	$108.95	11.708%	$121.7059	$121.71	$121.70	$121.70
Purchase #3	$138.53	9.782%	$152.081	$152.08	$152.10	$152.10
Purchase #4	$116.31	10.810%	$128.8831	$128.88	$128.90	$128.90
Purchase #5	$105.50	5.246%	$111.0345	$111.03	$111.05	$111.00
Purchase #6	$234.27	4.178%	$244.0578	$244.06	$244.05	$244.10
Purchase #7	$159.89	8.110%	$172.8571	$172.86	$172.85	$172.90
7 purchase totals =	$964.33		$1,044.9084	$1,044.91	$1,044.95	$1,045.00