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	$217.68	9.713%	$238.8233	$238.82	$238.80	$238.80
Purchase #2	$80.50	7.435%	$86.4852	$86.49	$86.50	$86.50
Purchase #3	$244.84	4.337%	$255.4587	$255.46	$255.45	$255.50
Purchase #4	$9.75	13.596%	$11.0756	$11.08	$11.10	$11.10
Purchase #5	$54.65	10.557%	$60.4194	$60.42	$60.40	$60.40
Purchase #6	$231.66	13.359%	$262.6075	$262.61	$262.60	$262.60
Purchase #7	$116.96	11.212%	$130.0736	$130.07	$130.05	$130.10
7 purchase totals =	$956.04		$1,044.9433	$1,044.95	$1,044.90	$1,045.00