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	$209.97	11.231%	$233.5517	$233.55	$233.55	$233.60
Purchase #2	$78.40	11.753%	$87.6144	$87.61	$87.60	$87.60
Purchase #3	$83.59	3.799%	$86.7656	$86.77	$86.75	$86.80
Purchase #4	$55.28	7.453%	$59.4	$59.40	$59.40	$59.40
Purchase #5	$236.87	7.846%	$255.4548	$255.45	$255.45	$255.50
Purchase #6	$20.58	5.217%	$21.6537	$21.65	$21.65	$21.70
Purchase #7	$249.39	9.167%	$272.2516	$272.25	$272.25	$272.30
7 purchase totals =	$934.08		$1,016.6918	$1,016.68	$1,016.65	$1,016.90