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	$104.82	8.787%	$114.0305	$114.03	$114.05	$114.00
Purchase #2	$100.68	7.526%	$108.2572	$108.26	$108.25	$108.30
Purchase #3	$213.51	4.664%	$223.4681	$223.47	$223.45	$223.50
Purchase #4	$33.64	13.531%	$38.1918	$38.19	$38.20	$38.20
Purchase #5	$172.46	5.807%	$182.4748	$182.47	$182.45	$182.50
Purchase #6	$188.50	6.551%	$200.8486	$200.85	$200.85	$200.80
Purchase #7	$46.41	8.365%	$50.2922	$50.29	$50.30	$50.30
7 purchase totals =	$860.02		$917.5632	$917.56	$917.55	$917.60