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	$87.43	6.167%	$92.8218	$92.82	$92.80	$92.80
Purchase #2	$10.30	7.419%	$11.0642	$11.06	$11.05	$11.10
Purchase #3	$54.81	4.633%	$57.3493	$57.35	$57.35	$57.30
Purchase #4	$137.67	5.306%	$144.9748	$144.97	$144.95	$145.00
Purchase #5	$93.85	12.511%	$105.5916	$105.59	$105.60	$105.60
Purchase #6	$90.84	5.478%	$95.8162	$95.82	$95.80	$95.80
Purchase #7	$187.64	9.568%	$205.5934	$205.59	$205.60	$205.60
7 purchase totals =	$662.54		$713.2113	$713.20	$713.15	$713.20