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	$162.81	6.162%	$172.8424	$172.84	$172.85	$172.80
Purchase #2	$30.47	11.131%	$33.8616	$33.86	$33.85	$33.90
Purchase #3	$66.42	13.522%	$75.4013	$75.40	$75.40	$75.40
Purchase #4	$174.48	10.836%	$193.3867	$193.39	$193.40	$193.40
Purchase #5	$216.77	4.694%	$226.9452	$226.95	$226.95	$226.90
Purchase #6	$205.82	8.152%	$222.5984	$222.60	$222.60	$222.60
Purchase #7	$143.38	6.667%	$152.9391	$152.94	$152.95	$152.90
7 purchase totals =	$1,000.15		$1,077.9747	$1,077.98	$1,078.00	$1,077.90