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	$19.26	6.206%	$20.4553	$20.46	$20.45	$20.50
Purchase #2	$11.49	10.869%	$12.7388	$12.74	$12.75	$12.70
Purchase #3	$57.96	5.385%	$61.0811	$61.08	$61.10	$61.10
Purchase #4	$85.88	4.563%	$89.7987	$89.80	$89.80	$89.80
Purchase #5	$210.90	5.271%	$222.0165	$222.02	$222.00	$222.00
Purchase #6	$245.27	6.613%	$261.4897	$261.49	$261.50	$261.50
Purchase #7	$30.67	11.686%	$34.2541	$34.25	$34.25	$34.30
7 purchase totals =	$661.43		$701.8342	$701.84	$701.85	$701.90