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	$56.64	9.395%	$61.9613	$61.96	$61.95	$62.00
Purchase #2	$49.37	8.137%	$53.3872	$53.39	$53.40	$53.40
Purchase #3	$112.78	4.580%	$117.9453	$117.95	$117.95	$117.90
Purchase #4	$119.45	3.218%	$123.2939	$123.29	$123.30	$123.30
Purchase #5	$201.57	6.859%	$215.3957	$215.40	$215.40	$215.40
Purchase #6	$65.72	8.671%	$71.4186	$71.42	$71.40	$71.40
Purchase #7	$117.86	5.553%	$124.4048	$124.40	$124.40	$124.40
7 purchase totals =	$723.39		$767.8068	$767.81	$767.80	$767.80