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	$57.31	10.685%	$63.4336	$63.43	$63.45	$63.40
Purchase #2	$111.50	11.174%	$123.959	$123.96	$123.95	$124.00
Purchase #3	$39.34	7.750%	$42.3889	$42.39	$42.40	$42.40
Purchase #4	$240.38	13.167%	$272.0308	$272.03	$272.05	$272.00
Purchase #5	$187.35	11.184%	$208.3032	$208.30	$208.30	$208.30
Purchase #6	$156.51	12.200%	$175.6042	$175.60	$175.60	$175.60
Purchase #7	$133.63	11.278%	$148.7008	$148.70	$148.70	$148.70
7 purchase totals =	$926.02		$1,034.4205	$1,034.41	$1,034.45	$1,034.40