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	$102.88	8.837%	$111.9715	$111.97	$111.95	$112.00
Purchase #2	$157.47	9.240%	$172.0202	$172.02	$172.00	$172.00
Purchase #3	$74.83	9.291%	$81.7825	$81.78	$81.80	$81.80
Purchase #4	$89.94	10.430%	$99.3207	$99.32	$99.30	$99.30
Purchase #5	$10.90	4.331%	$11.3721	$11.37	$11.35	$11.40
Purchase #6	$50.64	7.457%	$54.4162	$54.42	$54.40	$54.40
Purchase #7	$219.81	5.725%	$232.3941	$232.39	$232.40	$232.40
7 purchase totals =	$706.47		$763.2773	$763.27	$763.20	$763.30