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	$116.75	9.445%	$127.777	$127.78	$127.80	$127.80
Purchase #2	$40.93	5.516%	$43.1877	$43.19	$43.20	$43.20
Purchase #3	$236.62	10.665%	$261.8555	$261.86	$261.85	$261.90
Purchase #4	$11.63	8.288%	$12.5939	$12.59	$12.60	$12.60
Purchase #5	$54.69	3.129%	$56.4013	$56.40	$56.40	$56.40
Purchase #6	$167.77	10.523%	$185.4244	$185.42	$185.40	$185.40
Purchase #7	$59.62	11.105%	$66.2408	$66.24	$66.25	$66.20
7 purchase totals =	$688.01		$753.4806	$753.48	$753.50	$753.50