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	$102.48	8.660%	$111.3548	$111.35	$111.35	$111.40
Purchase #2	$82.91	11.438%	$92.3932	$92.39	$92.40	$92.40
Purchase #3	$204.55	6.341%	$217.5205	$217.52	$217.50	$217.50
Purchase #4	$181.64	13.731%	$206.581	$206.58	$206.60	$206.60
Purchase #5	$168.94	8.727%	$183.6834	$183.68	$183.70	$183.70
Purchase #6	$144.60	5.451%	$152.4821	$152.48	$152.50	$152.50
Purchase #7	$86.93	9.324%	$95.0354	$95.04	$95.05	$95.00
7 purchase totals =	$972.05		$1,059.0504	$1,059.04	$1,059.10	$1,059.10