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	$104.75	11.532%	$116.8298	$116.83	$116.85	$116.80
Purchase #2	$40.87	7.418%	$43.9017	$43.90	$43.90	$43.90
Purchase #3	$29.76	5.349%	$31.3519	$31.35	$31.35	$31.40
Purchase #4	$88.51	3.344%	$91.4698	$91.47	$91.45	$91.50
Purchase #5	$27.55	5.776%	$29.1413	$29.14	$29.15	$29.10
Purchase #6	$223.89	6.664%	$238.81	$238.81	$238.80	$238.80
Purchase #7	$156.91	11.609%	$175.1257	$175.13	$175.15	$175.10
7 purchase totals =	$672.24		$726.6302	$726.63	$726.65	$726.60