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	$118.42	3.141%	$122.1396	$122.14	$122.15	$122.10
Purchase #2	$30.28	11.235%	$33.682	$33.68	$33.70	$33.70
Purchase #3	$188.34	4.398%	$196.6232	$196.62	$196.60	$196.60
Purchase #4	$110.64	5.505%	$116.7307	$116.73	$116.75	$116.70
Purchase #5	$128.52	8.526%	$139.4776	$139.48	$139.50	$139.50
Purchase #6	$64.53	3.589%	$66.846	$66.85	$66.85	$66.80
Purchase #7	$27.25	10.612%	$30.1418	$30.14	$30.15	$30.10
7 purchase totals =	$667.98		$705.6409	$705.64	$705.70	$705.50