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	$169.72	12.507%	$190.9469	$190.95	$190.95	$190.90
Purchase #2	$38.80	12.339%	$43.5875	$43.59	$43.60	$43.60
Purchase #3	$58.36	12.691%	$65.7665	$65.77	$65.75	$65.80
Purchase #4	$87.42	13.671%	$99.3712	$99.37	$99.35	$99.40
Purchase #5	$210.89	8.778%	$229.4019	$229.40	$229.40	$229.40
Purchase #6	$205.66	4.186%	$214.2689	$214.27	$214.25	$214.30
Purchase #7	$195.62	10.695%	$216.5416	$216.54	$216.55	$216.50
7 purchase totals =	$966.47		$1,059.8845	$1,059.89	$1,059.85	$1,059.90