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	$197.72	9.174%	$215.8588	$215.86	$215.85	$215.90
Purchase #2	$111.70	10.253%	$123.1526	$123.15	$123.15	$123.20
Purchase #3	$54.58	10.126%	$60.1068	$60.11	$60.10	$60.10
Purchase #4	$129.43	12.448%	$145.5414	$145.54	$145.55	$145.50
Purchase #5	$97.45	3.609%	$100.967	$100.97	$100.95	$101.00
Purchase #6	$249.90	11.485%	$278.601	$278.60	$278.60	$278.60
Purchase #7	$29.98	5.280%	$31.5629	$31.56	$31.55	$31.60
7 purchase totals =	$870.76		$955.7905	$955.79	$955.75	$955.90