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	$172.68	10.263%	$190.4021	$190.40	$190.40	$190.40
Purchase #2	$46.31	8.760%	$50.3668	$50.37	$50.35	$50.40
Purchase #3	$154.61	5.345%	$162.8739	$162.87	$162.85	$162.90
Purchase #4	$123.81	7.814%	$133.4845	$133.48	$133.50	$133.50
Purchase #5	$220.50	11.800%	$246.519	$246.52	$246.50	$246.50
Purchase #6	$117.78	4.675%	$123.2862	$123.29	$123.30	$123.30
Purchase #7	$181.38	4.546%	$189.6255	$189.63	$189.65	$189.60
7 purchase totals =	$1,017.07		$1,096.5580	$1,096.56	$1,096.55	$1,096.60