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	$39.39	11.320%	$43.8489	$43.85	$43.85	$43.80
Purchase #2	$108.48	9.335%	$118.6066	$118.61	$118.60	$118.60
Purchase #3	$189.68	11.653%	$211.7834	$211.78	$211.80	$211.80
Purchase #4	$201.58	9.306%	$220.339	$220.34	$220.35	$220.30
Purchase #5	$100.37	11.348%	$111.76	$111.76	$111.75	$111.80
Purchase #6	$217.88	4.468%	$227.6149	$227.61	$227.60	$227.60
Purchase #7	$149.53	10.221%	$164.8135	$164.81	$164.80	$164.80
7 purchase totals =	$1,006.91		$1,098.7663	$1,098.76	$1,098.75	$1,098.70