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	$219.86	4.355%	$229.4349	$229.43	$229.45	$229.40
Purchase #2	$15.57	13.611%	$17.6892	$17.69	$17.70	$17.70
Purchase #3	$239.64	6.514%	$255.2501	$255.25	$255.25	$255.30
Purchase #4	$137.53	10.873%	$152.4836	$152.48	$152.50	$152.50
Purchase #5	$107.72	3.819%	$111.8338	$111.83	$111.85	$111.80
Purchase #6	$215.38	9.609%	$236.0759	$236.08	$236.10	$236.10
Purchase #7	$150.52	4.860%	$157.8353	$157.84	$157.85	$157.80
7 purchase totals =	$1,086.22		$1,160.6028	$1,160.60	$1,160.70	$1,160.60