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	$214.50	11.132%	$238.3781	$238.38	$238.40	$238.40
Purchase #2	$39.94	9.154%	$43.5961	$43.60	$43.60	$43.60
Purchase #3	$177.55	4.551%	$185.6303	$185.63	$185.65	$185.60
Purchase #4	$87.85	13.585%	$99.7844	$99.78	$99.80	$99.80
Purchase #5	$116.46	12.135%	$130.5924	$130.59	$130.60	$130.60
Purchase #6	$108.29	3.840%	$112.4483	$112.45	$112.45	$112.40
Purchase #7	$209.71	6.457%	$223.251	$223.25	$223.25	$223.30
7 purchase totals =	$954.30		$1,033.6806	$1,033.68	$1,033.75	$1,033.70