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	$206.37	4.653%	$215.9724	$215.97	$215.95	$216.00
Purchase #2	$100.76	13.273%	$114.1339	$114.13	$114.15	$114.10
Purchase #3	$158.30	13.171%	$179.1497	$179.15	$179.15	$179.10
Purchase #4	$102.25	6.455%	$108.8502	$108.85	$108.85	$108.90
Purchase #5	$222.30	3.676%	$230.4717	$230.47	$230.45	$230.50
Purchase #6	$85.28	10.546%	$94.2736	$94.27	$94.25	$94.30
Purchase #7	$177.40	6.811%	$189.4827	$189.48	$189.50	$189.50
7 purchase totals =	$1,052.66		$1,132.3342	$1,132.32	$1,132.30	$1,132.40