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	$233.90	9.279%	$255.6036	$255.60	$255.60	$255.60
Purchase #2	$240.75	4.447%	$251.4562	$251.46	$251.45	$251.50
Purchase #3	$42.86	7.305%	$45.9909	$45.99	$46.00	$46.00
Purchase #4	$173.56	3.666%	$179.9227	$179.92	$179.90	$179.90
Purchase #5	$241.89	5.584%	$255.3971	$255.40	$255.40	$255.40
Purchase #6	$106.81	4.348%	$111.4541	$111.45	$111.45	$111.50
Purchase #7	$31.82	9.342%	$34.7926	$34.79	$34.80	$34.80
7 purchase totals =	$1,071.59		$1,134.6172	$1,134.61	$1,134.60	$1,134.70