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	$232.40	9.497%	$254.471	$254.47	$254.45	$254.50
Purchase #2	$91.65	9.793%	$100.6253	$100.63	$100.65	$100.60
Purchase #3	$179.52	11.414%	$200.0104	$200.01	$200.00	$200.00
Purchase #4	$238.71	6.557%	$254.3622	$254.36	$254.35	$254.40
Purchase #5	$49.50	4.314%	$51.6354	$51.64	$51.65	$51.60
Purchase #6	$231.85	11.527%	$258.5753	$258.58	$258.60	$258.60
Purchase #7	$72.94	13.582%	$82.8467	$82.85	$82.85	$82.80
7 purchase totals =	$1,096.57		$1,202.5263	$1,202.54	$1,202.55	$1,202.50