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	$99.56	13.256%	$112.7577	$112.76	$112.75	$112.80
Purchase #2	$216.72	13.626%	$246.2503	$246.25	$246.25	$246.30
Purchase #3	$96.98	4.314%	$101.1637	$101.16	$101.15	$101.20
Purchase #4	$227.90	7.823%	$245.7286	$245.73	$245.75	$245.70
Purchase #5	$212.25	5.340%	$223.5842	$223.58	$223.60	$223.60
Purchase #6	$207.46	7.181%	$222.3577	$222.36	$222.35	$222.40
Purchase #7	$102.60	8.733%	$111.5601	$111.56	$111.55	$111.60
7 purchase totals =	$1,163.47		$1,263.4023	$1,263.40	$1,263.40	$1,263.60