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	$196.43	13.133%	$222.2272	$222.23	$222.25	$222.20
Purchase #2	$66.61	12.438%	$74.895	$74.90	$74.90	$74.90
Purchase #3	$75.59	6.496%	$80.5003	$80.50	$80.50	$80.50
Purchase #4	$84.65	7.416%	$90.9276	$90.93	$90.95	$90.90
Purchase #5	$17.56	9.315%	$19.1957	$19.20	$19.20	$19.20
Purchase #6	$78.56	10.807%	$87.05	$87.05	$87.05	$87.10
Purchase #7	$136.28	10.587%	$150.708	$150.71	$150.70	$150.70
7 purchase totals =	$655.68		$725.5038	$725.52	$725.55	$725.50