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	$16.58	5.235%	$17.448	$17.45	$17.45	$17.40
Purchase #2	$159.58	8.163%	$172.6065	$172.61	$172.60	$172.60
Purchase #3	$201.50	7.567%	$216.7475	$216.75	$216.75	$216.70
Purchase #4	$146.53	4.234%	$152.7341	$152.73	$152.75	$152.70
Purchase #5	$49.41	6.697%	$52.719	$52.72	$52.70	$52.70
Purchase #6	$182.80	7.236%	$196.0274	$196.03	$196.05	$196.00
Purchase #7	$196.49	10.346%	$216.8189	$216.82	$216.80	$216.80
7 purchase totals =	$952.89		$1,025.1014	$1,025.11	$1,025.10	$1,024.90