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	$44.64	6.771%	$47.6626	$47.66	$47.65	$47.70
Purchase #2	$248.58	12.831%	$280.4753	$280.48	$280.50	$280.50
Purchase #3	$81.46	7.483%	$87.5557	$87.56	$87.55	$87.60
Purchase #4	$19.59	6.440%	$20.8516	$20.85	$20.85	$20.90
Purchase #5	$172.78	9.199%	$188.674	$188.67	$188.65	$188.70
Purchase #6	$56.39	5.316%	$59.3877	$59.39	$59.40	$59.40
Purchase #7	$46.52	11.419%	$51.8321	$51.83	$51.85	$51.80
7 purchase totals =	$669.96		$736.4390	$736.44	$736.45	$736.60