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	$130.55	11.122%	$145.0698	$145.07	$145.05	$145.10
Purchase #2	$105.53	5.536%	$111.3721	$111.37	$111.35	$111.40
Purchase #3	$128.68	13.366%	$145.8794	$145.88	$145.90	$145.90
Purchase #4	$125.83	4.487%	$131.476	$131.48	$131.50	$131.50
Purchase #5	$248.34	6.209%	$263.7594	$263.76	$263.75	$263.80
Purchase #6	$192.51	8.455%	$208.7867	$208.79	$208.80	$208.80
Purchase #7	$105.28	11.823%	$117.7273	$117.73	$117.75	$117.70
7 purchase totals =	$1,036.72		$1,124.0707	$1,124.08	$1,124.10	$1,124.20