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	$219.52	6.205%	$233.1412	$233.14	$233.15	$233.10
Purchase #2	$138.82	3.287%	$143.383	$143.38	$143.40	$143.40
Purchase #3	$91.79	3.369%	$94.8824	$94.88	$94.90	$94.90
Purchase #4	$45.80	13.339%	$51.9093	$51.91	$51.90	$51.90
Purchase #5	$233.77	12.247%	$262.3998	$262.40	$262.40	$262.40
Purchase #6	$172.95	9.860%	$190.0029	$190.00	$190.00	$190.00
Purchase #7	$34.81	4.783%	$36.475	$36.48	$36.50	$36.50
7 purchase totals =	$937.46		$1,012.1936	$1,012.19	$1,012.25	$1,012.20