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	$57.64	8.759%	$62.6887	$62.69	$62.70	$62.70
Purchase #2	$29.83	12.581%	$33.5829	$33.58	$33.60	$33.60
Purchase #3	$200.51	11.509%	$223.5867	$223.59	$223.60	$223.60
Purchase #4	$206.59	9.162%	$225.5178	$225.52	$225.50	$225.50
Purchase #5	$125.44	10.243%	$138.2888	$138.29	$138.30	$138.30
Purchase #6	$176.56	11.803%	$197.3994	$197.40	$197.40	$197.40
Purchase #7	$206.36	4.199%	$215.0251	$215.03	$215.05	$215.00
7 purchase totals =	$1,002.93		$1,096.0894	$1,096.10	$1,096.15	$1,096.10