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	$184.98	4.305%	$192.9434	$192.94	$192.95	$192.90
Purchase #2	$210.29	13.327%	$238.3153	$238.32	$238.30	$238.30
Purchase #3	$207.86	6.733%	$221.8552	$221.86	$221.85	$221.90
Purchase #4	$126.48	8.574%	$137.3244	$137.32	$137.30	$137.30
Purchase #5	$40.78	7.308%	$43.7602	$43.76	$43.75	$43.80
Purchase #6	$213.98	5.228%	$225.1669	$225.17	$225.15	$225.20
Purchase #7	$91.25	11.333%	$101.5914	$101.59	$101.60	$101.60
7 purchase totals =	$1,075.62		$1,160.9568	$1,160.96	$1,160.90	$1,161.00