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	$61.25	5.647%	$64.7088	$64.71	$64.70	$64.70
Purchase #2	$249.35	12.487%	$280.4863	$280.49	$280.50	$280.50
Purchase #3	$75.47	11.750%	$84.3377	$84.34	$84.35	$84.30
Purchase #4	$152.87	12.858%	$172.526	$172.53	$172.55	$172.50
Purchase #5	$201.41	6.443%	$214.3868	$214.39	$214.40	$214.40
Purchase #6	$114.89	10.574%	$127.0385	$127.04	$127.05	$127.00
Purchase #7	$121.32	4.305%	$126.5428	$126.54	$126.55	$126.50
7 purchase totals =	$976.56		$1,070.0269	$1,070.04	$1,070.10	$1,069.90