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	$116.85	5.769%	$123.5911	$123.59	$123.60	$123.60
Purchase #2	$68.46	6.576%	$72.9619	$72.96	$72.95	$73.00
Purchase #3	$78.29	6.736%	$83.5636	$83.56	$83.55	$83.60
Purchase #4	$85.67	13.768%	$97.465	$97.47	$97.45	$97.50
Purchase #5	$212.53	4.637%	$222.385	$222.39	$222.40	$222.40
Purchase #6	$164.29	7.180%	$176.086	$176.09	$176.10	$176.10
Purchase #7	$105.37	13.646%	$119.7488	$119.75	$119.75	$119.70
7 purchase totals =	$831.46		$895.8014	$895.81	$895.80	$895.90