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	$198.98	7.772%	$214.4447	$214.44	$214.45	$214.40
Purchase #2	$144.56	5.509%	$152.5238	$152.52	$152.50	$152.50
Purchase #3	$23.48	10.462%	$25.9365	$25.94	$25.95	$25.90
Purchase #4	$107.50	4.490%	$112.3268	$112.33	$112.35	$112.30
Purchase #5	$148.86	6.268%	$158.1905	$158.19	$158.20	$158.20
Purchase #6	$250.77	5.266%	$263.9755	$263.98	$264.00	$264.00
Purchase #7	$96.56	7.873%	$104.1622	$104.16	$104.15	$104.20
7 purchase totals =	$970.71		$1,031.5600	$1,031.56	$1,031.60	$1,031.50