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	$209.84	10.536%	$231.9487	$231.95	$231.95	$231.90
Purchase #2	$217.39	12.161%	$243.8268	$243.83	$243.85	$243.80
Purchase #3	$111.72	10.489%	$123.4383	$123.44	$123.45	$123.40
Purchase #4	$129.57	13.292%	$146.7924	$146.79	$146.80	$146.80
Purchase #5	$56.89	8.327%	$61.6272	$61.63	$61.65	$61.60
Purchase #6	$128.51	3.476%	$132.977	$132.98	$133.00	$133.00
Purchase #7	$172.35	3.525%	$178.4253	$178.43	$178.45	$178.40
7 purchase totals =	$1,026.27		$1,119.0357	$1,119.05	$1,119.15	$1,118.90