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	$161.96	6.488%	$172.468	$172.47	$172.45	$172.50
Purchase #2	$104.88	5.451%	$110.597	$110.60	$110.60	$110.60
Purchase #3	$146.73	13.207%	$166.1086	$166.11	$166.10	$166.10
Purchase #4	$14.25	7.856%	$15.3695	$15.37	$15.35	$15.40
Purchase #5	$110.39	7.416%	$118.5765	$118.58	$118.60	$118.60
Purchase #6	$241.36	5.826%	$255.4216	$255.42	$255.40	$255.40
Purchase #7	$108.55	3.623%	$112.4828	$112.48	$112.50	$112.50
7 purchase totals =	$888.12		$951.0240	$951.03	$951.00	$951.10