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	$65.98	9.337%	$72.1406	$72.14	$72.15	$72.10
Purchase #2	$123.65	3.581%	$128.0779	$128.08	$128.10	$128.10
Purchase #3	$108.43	3.863%	$112.6187	$112.62	$112.60	$112.60
Purchase #4	$122.78	8.322%	$132.9978	$133.00	$133.00	$133.00
Purchase #5	$168.67	8.270%	$182.619	$182.62	$182.60	$182.60
Purchase #6	$12.96	4.256%	$13.5116	$13.51	$13.50	$13.50
Purchase #7	$53.52	10.870%	$59.3376	$59.34	$59.35	$59.30
7 purchase totals =	$655.99		$701.3032	$701.31	$701.30	$701.20