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	$60.95	10.221%	$67.1797	$67.18	$67.20	$67.20
Purchase #2	$73.52	9.422%	$80.4471	$80.45	$80.45	$80.40
Purchase #3	$9.80	3.214%	$10.115	$10.12	$10.10	$10.10
Purchase #4	$11.90	5.701%	$12.5784	$12.58	$12.60	$12.60
Purchase #5	$202.93	4.336%	$211.729	$211.73	$211.75	$211.70
Purchase #6	$88.38	13.694%	$100.4828	$100.48	$100.50	$100.50
Purchase #7	$73.46	13.633%	$83.4748	$83.47	$83.45	$83.50
7 purchase totals =	$520.94		$566.0068	$566.01	$566.05	$566.00