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	$219.70	7.222%	$235.5667	$235.57	$235.55	$235.60
Purchase #2	$103.80	7.555%	$111.6421	$111.64	$111.65	$111.60
Purchase #3	$212.98	13.580%	$241.9027	$241.90	$241.90	$241.90
Purchase #4	$163.52	11.616%	$182.5145	$182.51	$182.50	$182.50
Purchase #5	$117.81	9.167%	$128.6096	$128.61	$128.60	$128.60
Purchase #6	$243.31	5.161%	$255.8672	$255.87	$255.85	$255.90
Purchase #7	$61.40	10.722%	$67.9833	$67.98	$68.00	$68.00
7 purchase totals =	$1,122.52		$1,224.0861	$1,224.08	$1,224.05	$1,224.10