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	$226.74	12.191%	$254.3819	$254.38	$254.40	$254.40
Purchase #2	$236.75	7.866%	$255.3728	$255.37	$255.35	$255.40
Purchase #3	$230.89	3.120%	$238.0938	$238.09	$238.10	$238.10
Purchase #4	$190.61	6.465%	$202.9329	$202.93	$202.95	$202.90
Purchase #5	$44.58	6.386%	$47.4269	$47.43	$47.45	$47.40
Purchase #6	$56.38	4.725%	$59.044	$59.04	$59.05	$59.00
Purchase #7	$86.81	9.828%	$95.3417	$95.34	$95.35	$95.30
7 purchase totals =	$1,072.76		$1,152.5940	$1,152.58	$1,152.65	$1,152.50