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	$200.46	3.625%	$207.7267	$207.73	$207.75	$207.70
Purchase #2	$40.90	9.632%	$44.8395	$44.84	$44.85	$44.80
Purchase #3	$218.48	10.725%	$241.912	$241.91	$241.90	$241.90
Purchase #4	$169.40	11.508%	$188.8946	$188.89	$188.90	$188.90
Purchase #5	$105.99	6.132%	$112.4893	$112.49	$112.50	$112.50
Purchase #6	$190.34	13.184%	$215.4344	$215.43	$215.45	$215.40
Purchase #7	$132.72	5.200%	$139.6214	$139.62	$139.60	$139.60
7 purchase totals =	$1,058.29		$1,150.9179	$1,150.91	$1,150.95	$1,150.80