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	$241.85	8.693%	$262.874	$262.87	$262.85	$262.90
Purchase #2	$204.85	10.692%	$226.7526	$226.75	$226.75	$226.80
Purchase #3	$52.99	4.294%	$55.2654	$55.27	$55.25	$55.30
Purchase #4	$175.67	5.635%	$185.569	$185.57	$185.55	$185.60
Purchase #5	$42.89	8.496%	$46.5339	$46.53	$46.55	$46.50
Purchase #6	$187.69	3.676%	$194.5895	$194.59	$194.60	$194.60
Purchase #7	$122.77	4.803%	$128.6666	$128.67	$128.65	$128.70
7 purchase totals =	$1,028.71		$1,100.2510	$1,100.25	$1,100.20	$1,100.40