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	$237.29	3.503%	$245.6023	$245.60	$245.60	$245.60
Purchase #2	$231.96	5.522%	$244.7688	$244.77	$244.75	$244.80
Purchase #3	$7.79	13.211%	$8.8191	$8.82	$8.80	$8.80
Purchase #4	$58.64	4.276%	$61.1474	$61.15	$61.15	$61.10
Purchase #5	$249.32	10.538%	$275.5933	$275.59	$275.60	$275.60
Purchase #6	$24.98	6.143%	$26.5145	$26.51	$26.50	$26.50
Purchase #7	$212.66	4.784%	$222.8337	$222.83	$222.85	$222.80
7 purchase totals =	$1,022.64		$1,085.2791	$1,085.27	$1,085.25	$1,085.20