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	$64.53	6.575%	$68.7728	$68.77	$68.75	$68.80
Purchase #2	$224.34	4.136%	$233.6187	$233.62	$233.60	$233.60
Purchase #3	$201.61	3.524%	$208.7147	$208.71	$208.70	$208.70
Purchase #4	$54.56	3.589%	$56.5182	$56.52	$56.50	$56.50
Purchase #5	$97.72	5.756%	$103.3448	$103.34	$103.35	$103.30
Purchase #6	$118.88	6.105%	$126.1376	$126.14	$126.15	$126.10
Purchase #7	$198.32	10.378%	$218.9016	$218.90	$218.90	$218.90
7 purchase totals =	$959.96		$1,016.0084	$1,016.00	$1,015.95	$1,015.90