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	$151.40	6.715%	$161.5665	$161.57	$161.55	$161.60
Purchase #2	$17.30	7.566%	$18.6089	$18.61	$18.60	$18.60
Purchase #3	$167.99	10.210%	$185.1418	$185.14	$185.15	$185.10
Purchase #4	$242.27	13.120%	$274.0558	$274.06	$274.05	$274.10
Purchase #5	$85.89	6.128%	$91.1533	$91.15	$91.15	$91.20
Purchase #6	$87.89	4.360%	$91.722	$91.72	$91.70	$91.70
Purchase #7	$172.34	11.476%	$192.1177	$192.12	$192.10	$192.10
7 purchase totals =	$925.08		$1,014.3660	$1,014.37	$1,014.30	$1,014.40