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	$233.26	4.340%	$243.3835	$243.38	$243.40	$243.40
Purchase #2	$244.68	7.249%	$262.4169	$262.42	$262.40	$262.40
Purchase #3	$7.41	6.365%	$7.8816	$7.88	$7.90	$7.90
Purchase #4	$97.90	6.265%	$104.0334	$104.03	$104.05	$104.00
Purchase #5	$238.90	3.294%	$246.7694	$246.77	$246.75	$246.80
Purchase #6	$40.31	12.752%	$45.4503	$45.45	$45.45	$45.50
Purchase #7	$93.53	7.632%	$100.6682	$100.67	$100.65	$100.70
7 purchase totals =	$955.99		$1,010.6033	$1,010.60	$1,010.60	$1,010.70