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	$188.55	9.208%	$205.9117	$205.91	$205.90	$205.90
Purchase #2	$80.65	8.508%	$87.5117	$87.51	$87.50	$87.50
Purchase #3	$59.35	3.779%	$61.5928	$61.59	$61.60	$61.60
Purchase #4	$14.70	4.744%	$15.3974	$15.40	$15.40	$15.40
Purchase #5	$122.94	7.616%	$132.3031	$132.30	$132.30	$132.30
Purchase #6	$142.44	7.643%	$153.3267	$153.33	$153.35	$153.30
Purchase #7	$37.72	13.702%	$42.8884	$42.89	$42.90	$42.90
7 purchase totals =	$646.35		$698.9318	$698.93	$698.95	$698.90