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	$130.27	10.820%	$144.3652	$144.37	$144.35	$144.40
Purchase #2	$176.60	8.465%	$191.5492	$191.55	$191.55	$191.50
Purchase #3	$61.41	5.495%	$64.7845	$64.78	$64.80	$64.80
Purchase #4	$56.88	10.456%	$62.8274	$62.83	$62.85	$62.80
Purchase #5	$9.64	5.243%	$10.1454	$10.15	$10.15	$10.10
Purchase #6	$196.57	8.104%	$212.5	$212.50	$212.50	$212.50
Purchase #7	$233.56	13.826%	$265.852	$265.85	$265.85	$265.90
7 purchase totals =	$864.93		$952.0237	$952.03	$952.05	$952.00