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	$165.27	5.399%	$174.1929	$174.19	$174.20	$174.20
Purchase #2	$154.34	11.685%	$172.3746	$172.37	$172.35	$172.40
Purchase #3	$213.34	6.764%	$227.7703	$227.77	$227.75	$227.80
Purchase #4	$29.71	11.692%	$33.1837	$33.18	$33.20	$33.20
Purchase #5	$132.89	9.550%	$145.581	$145.58	$145.60	$145.60
Purchase #6	$149.57	3.399%	$154.6539	$154.65	$154.65	$154.70
Purchase #7	$220.30	11.281%	$245.152	$245.15	$245.15	$245.20
7 purchase totals =	$1,065.42		$1,152.9084	$1,152.89	$1,152.90	$1,153.10