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	$217.32	9.114%	$237.1265	$237.13	$237.15	$237.10
Purchase #2	$136.59	8.638%	$148.3886	$148.39	$148.40	$148.40
Purchase #3	$172.96	3.515%	$179.0395	$179.04	$179.05	$179.00
Purchase #4	$10.60	13.847%	$12.0678	$12.07	$12.05	$12.10
Purchase #5	$141.71	6.690%	$151.1904	$151.19	$151.20	$151.20
Purchase #6	$146.51	10.387%	$161.728	$161.73	$161.75	$161.70
Purchase #7	$159.85	7.631%	$172.0482	$172.05	$172.05	$172.00
7 purchase totals =	$985.54		$1,061.5890	$1,061.60	$1,061.65	$1,061.50