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	$161.98	8.422%	$175.622	$175.62	$175.60	$175.60
Purchase #2	$15.88	9.454%	$17.3813	$17.38	$17.40	$17.40
Purchase #3	$10.50	3.189%	$10.8348	$10.83	$10.85	$10.80
Purchase #4	$153.86	11.680%	$171.8308	$171.83	$171.85	$171.80
Purchase #5	$37.31	11.629%	$41.6488	$41.65	$41.65	$41.60
Purchase #6	$205.65	9.667%	$225.5302	$225.53	$225.55	$225.50
Purchase #7	$74.80	10.691%	$82.7969	$82.80	$82.80	$82.80
7 purchase totals =	$659.98		$725.6448	$725.64	$725.70	$725.50