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	$192.32	11.507%	$214.4503	$214.45	$214.45	$214.50
Purchase #2	$24.35	4.811%	$25.5215	$25.52	$25.50	$25.50
Purchase #3	$239.64	8.700%	$260.4887	$260.49	$260.50	$260.50
Purchase #4	$244.82	11.665%	$273.3783	$273.38	$273.40	$273.40
Purchase #5	$146.64	9.253%	$160.2086	$160.21	$160.20	$160.20
Purchase #6	$44.53	12.854%	$50.2539	$50.25	$50.25	$50.30
Purchase #7	$100.59	11.827%	$112.4868	$112.49	$112.50	$112.50
7 purchase totals =	$992.89		$1,096.7881	$1,096.79	$1,096.80	$1,096.90