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	$163.36	6.201%	$173.49	$173.49	$173.50	$173.50
Purchase #2	$204.77	6.119%	$217.2999	$217.30	$217.30	$217.30
Purchase #3	$245.81	7.184%	$263.469	$263.47	$263.45	$263.50
Purchase #4	$125.70	13.456%	$142.6142	$142.61	$142.60	$142.60
Purchase #5	$174.88	5.863%	$185.1332	$185.13	$185.15	$185.10
Purchase #6	$69.88	12.335%	$78.4997	$78.50	$78.50	$78.50
Purchase #7	$80.51	6.393%	$85.657	$85.66	$85.65	$85.70
7 purchase totals =	$1,064.91		$1,146.1630	$1,146.16	$1,146.15	$1,146.20