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	$196.68	13.301%	$222.8404	$222.84	$222.85	$222.80
Purchase #2	$224.26	7.305%	$240.6422	$240.64	$240.65	$240.60
Purchase #3	$137.83	5.703%	$145.6904	$145.69	$145.70	$145.70
Purchase #4	$55.95	13.795%	$63.6683	$63.67	$63.65	$63.70
Purchase #5	$42.78	4.339%	$44.6362	$44.64	$44.65	$44.60
Purchase #6	$181.29	10.612%	$200.5285	$200.53	$200.55	$200.50
Purchase #7	$172.90	3.267%	$178.5486	$178.55	$178.55	$178.50
7 purchase totals =	$1,011.69		$1,096.5546	$1,096.56	$1,096.60	$1,096.40