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	$200.56	8.223%	$217.052	$217.05	$217.05	$217.10
Purchase #2	$209.73	10.679%	$232.1271	$232.13	$232.15	$232.10
Purchase #3	$250.84	4.619%	$262.4263	$262.43	$262.45	$262.40
Purchase #4	$116.39	6.305%	$123.7284	$123.73	$123.75	$123.70
Purchase #5	$231.82	5.607%	$244.8181	$244.82	$244.80	$244.80
Purchase #6	$204.54	8.704%	$222.3432	$222.34	$222.35	$222.30
Purchase #7	$78.51	4.198%	$81.8058	$81.81	$81.80	$81.80
7 purchase totals =	$1,292.39		$1,384.3009	$1,384.31	$1,384.35	$1,384.20