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	$210.62	5.749%	$222.7285	$222.73	$222.75	$222.70
Purchase #2	$206.57	10.185%	$227.6092	$227.61	$227.60	$227.60
Purchase #3	$63.65	10.589%	$70.3899	$70.39	$70.40	$70.40
Purchase #4	$196.80	4.640%	$205.9315	$205.93	$205.95	$205.90
Purchase #5	$213.65	4.161%	$222.54	$222.54	$222.55	$222.50
Purchase #6	$103.90	4.311%	$108.3791	$108.38	$108.40	$108.40
Purchase #7	$17.82	13.462%	$20.2189	$20.22	$20.20	$20.20
7 purchase totals =	$1,013.01		$1,077.7971	$1,077.80	$1,077.85	$1,077.70