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	$208.96	3.368%	$215.9978	$216.00	$216.00	$216.00
Purchase #2	$64.88	4.257%	$67.6419	$67.64	$67.65	$67.60
Purchase #3	$116.97	13.393%	$132.6358	$132.64	$132.65	$132.60
Purchase #4	$244.83	11.242%	$272.3538	$272.35	$272.35	$272.40
Purchase #5	$220.47	13.333%	$249.8653	$249.87	$249.85	$249.90
Purchase #6	$179.28	3.649%	$185.8219	$185.82	$185.80	$185.80
Purchase #7	$130.27	7.145%	$139.5778	$139.58	$139.60	$139.60
7 purchase totals =	$1,165.66		$1,263.8943	$1,263.90	$1,263.90	$1,263.90