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	$244.92	8.145%	$264.8687	$264.87	$264.85	$264.90
Purchase #2	$147.63	7.121%	$158.1427	$158.14	$158.15	$158.10
Purchase #3	$145.86	11.185%	$162.1744	$162.17	$162.15	$162.20
Purchase #4	$95.88	4.196%	$99.9031	$99.90	$99.90	$99.90
Purchase #5	$172.60	7.341%	$185.2706	$185.27	$185.25	$185.30
Purchase #6	$89.62	11.181%	$99.6404	$99.64	$99.65	$99.60
Purchase #7	$58.76	10.633%	$65.008	$65.01	$65.00	$65.00
7 purchase totals =	$955.27		$1,035.0079	$1,035.00	$1,034.95	$1,035.00