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	$134.37	9.322%	$146.896	$146.90	$146.90	$146.90
Purchase #2	$46.38	9.698%	$50.8779	$50.88	$50.90	$50.90
Purchase #3	$159.59	10.651%	$176.5879	$176.59	$176.60	$176.60
Purchase #4	$80.26	3.811%	$83.3187	$83.32	$83.30	$83.30
Purchase #5	$208.94	6.492%	$222.5044	$222.50	$222.50	$222.50
Purchase #6	$237.91	9.452%	$260.3973	$260.40	$260.40	$260.40
Purchase #7	$226.94	13.443%	$257.4475	$257.45	$257.45	$257.40
7 purchase totals =	$1,094.39		$1,198.0297	$1,198.04	$1,198.05	$1,198.00