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	$119.81	6.715%	$127.8552	$127.86	$127.85	$127.90
Purchase #2	$236.33	8.547%	$256.5291	$256.53	$256.55	$256.50
Purchase #3	$140.25	10.243%	$154.6158	$154.62	$154.60	$154.60
Purchase #4	$187.86	11.397%	$209.2704	$209.27	$209.25	$209.30
Purchase #5	$64.26	3.558%	$66.5464	$66.55	$66.55	$66.50
Purchase #6	$188.95	10.284%	$208.3816	$208.38	$208.40	$208.40
Purchase #7	$131.64	5.864%	$139.3594	$139.36	$139.35	$139.40
7 purchase totals =	$1,069.10		$1,162.5579	$1,162.57	$1,162.55	$1,162.60