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	$57.67	7.744%	$62.136	$62.14	$62.15	$62.10
Purchase #2	$99.89	12.126%	$112.0027	$112.00	$112.00	$112.00
Purchase #3	$234.57	13.581%	$266.427	$266.43	$266.45	$266.40
Purchase #4	$115.62	10.348%	$127.5844	$127.58	$127.60	$127.60
Purchase #5	$139.85	8.623%	$151.9093	$151.91	$151.90	$151.90
Purchase #6	$92.61	9.218%	$101.1468	$101.15	$101.15	$101.10
Purchase #7	$131.51	5.214%	$138.3669	$138.37	$138.35	$138.40
7 purchase totals =	$871.72		$959.5731	$959.58	$959.60	$959.50