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	$144.99	5.255%	$152.6092	$152.61	$152.60	$152.60
Purchase #2	$85.34	7.240%	$91.5186	$91.52	$91.50	$91.50
Purchase #3	$19.88	11.110%	$22.0887	$22.09	$22.10	$22.10
Purchase #4	$18.48	3.539%	$19.134	$19.13	$19.15	$19.10
Purchase #5	$87.98	12.709%	$99.1614	$99.16	$99.15	$99.20
Purchase #6	$28.67	3.798%	$29.7589	$29.76	$29.75	$29.80
Purchase #7	$52.56	8.727%	$57.1469	$57.15	$57.15	$57.10
7 purchase totals =	$437.90		$471.4177	$471.42	$471.40	$471.40