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	$224.75	7.396%	$241.3725	$241.37	$241.35	$241.40
Purchase #2	$40.78	4.517%	$42.622	$42.62	$42.60	$42.60
Purchase #3	$63.48	9.442%	$69.4738	$69.47	$69.45	$69.50
Purchase #4	$78.75	11.700%	$87.9638	$87.96	$87.95	$88.00
Purchase #5	$238.78	13.290%	$270.5139	$270.51	$270.50	$270.50
Purchase #6	$163.81	10.445%	$180.92	$180.92	$180.90	$180.90
Purchase #7	$145.52	3.416%	$150.491	$150.49	$150.50	$150.50
7 purchase totals =	$955.87		$1,043.3570	$1,043.34	$1,043.25	$1,043.40