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	$161.89	4.607%	$169.3483	$169.35	$169.35	$169.30
Purchase #2	$157.54	13.511%	$178.8252	$178.83	$178.85	$178.80
Purchase #3	$169.35	4.486%	$176.947	$176.95	$176.95	$176.90
Purchase #4	$215.47	11.169%	$239.5358	$239.54	$239.55	$239.50
Purchase #5	$111.39	4.557%	$116.466	$116.47	$116.45	$116.50
Purchase #6	$136.57	6.178%	$145.0073	$145.01	$145.00	$145.00
Purchase #7	$117.29	8.394%	$127.1353	$127.14	$127.15	$127.10
7 purchase totals =	$1,069.50		$1,153.2649	$1,153.29	$1,153.30	$1,153.10