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	$129.69	12.591%	$146.0193	$146.02	$146.00	$146.00
Purchase #2	$127.64	7.256%	$136.9016	$136.90	$136.90	$136.90
Purchase #3	$63.55	4.410%	$66.3526	$66.35	$66.35	$66.40
Purchase #4	$134.52	8.586%	$146.0699	$146.07	$146.05	$146.10
Purchase #5	$134.53	13.328%	$152.4602	$152.46	$152.45	$152.50
Purchase #6	$231.80	11.554%	$258.5822	$258.58	$258.60	$258.60
Purchase #7	$168.83	6.362%	$179.571	$179.57	$179.55	$179.60
7 purchase totals =	$990.56		$1,085.9568	$1,085.95	$1,085.90	$1,086.10