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	$118.65	6.153%	$125.9505	$125.95	$125.95	$126.00
Purchase #2	$24.78	11.848%	$27.7159	$27.72	$27.70	$27.70
Purchase #3	$18.77	13.473%	$21.2989	$21.30	$21.30	$21.30
Purchase #4	$33.45	11.555%	$37.3151	$37.32	$37.30	$37.30
Purchase #5	$194.29	3.246%	$200.5967	$200.60	$200.60	$200.60
Purchase #6	$50.63	13.378%	$57.4033	$57.40	$57.40	$57.40
Purchase #7	$124.47	10.124%	$137.0713	$137.07	$137.05	$137.10
7 purchase totals =	$565.04		$607.3517	$607.36	$607.30	$607.40