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	$63.33	5.719%	$66.9518	$66.95	$66.95	$67.00
Purchase #2	$194.86	13.228%	$220.6361	$220.64	$220.65	$220.60
Purchase #3	$84.44	6.459%	$89.894	$89.89	$89.90	$89.90
Purchase #4	$160.55	10.452%	$177.3307	$177.33	$177.35	$177.30
Purchase #5	$97.51	6.495%	$103.8433	$103.84	$103.85	$103.80
Purchase #6	$225.43	3.661%	$233.683	$233.68	$233.70	$233.70
Purchase #7	$112.66	9.762%	$123.6579	$123.66	$123.65	$123.70
7 purchase totals =	$938.78		$1,015.9968	$1,015.99	$1,016.05	$1,016.00