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	$20.70	10.850%	$22.946	$22.95	$22.95	$22.90
Purchase #2	$100.63	4.143%	$104.7991	$104.80	$104.80	$104.80
Purchase #3	$131.32	13.682%	$149.2872	$149.29	$149.30	$149.30
Purchase #4	$80.98	11.509%	$90.3	$90.30	$90.30	$90.30
Purchase #5	$10.28	9.853%	$11.2929	$11.29	$11.30	$11.30
Purchase #6	$220.91	6.132%	$234.4562	$234.46	$234.45	$234.50
Purchase #7	$102.48	10.748%	$113.4946	$113.49	$113.50	$113.50
7 purchase totals =	$667.30		$726.5760	$726.58	$726.60	$726.60