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	$112.37	13.618%	$127.6725	$127.67	$127.65	$127.70
Purchase #2	$13.53	7.246%	$14.5104	$14.51	$14.50	$14.50
Purchase #3	$63.97	5.683%	$67.6054	$67.61	$67.60	$67.60
Purchase #4	$25.95	4.508%	$27.1198	$27.12	$27.10	$27.10
Purchase #5	$125.85	7.107%	$134.7942	$134.79	$134.80	$134.80
Purchase #6	$104.68	6.637%	$111.6276	$111.63	$111.65	$111.60
Purchase #7	$124.62	5.360%	$131.2996	$131.30	$131.30	$131.30
7 purchase totals =	$570.97		$614.6295	$614.63	$614.60	$614.60