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	$94.65	7.739%	$101.975	$101.98	$102.00	$102.00
Purchase #2	$177.87	5.548%	$187.7382	$187.74	$187.75	$187.70
Purchase #3	$217.67	6.362%	$231.5182	$231.52	$231.50	$231.50
Purchase #4	$185.78	6.617%	$198.0731	$198.07	$198.05	$198.10
Purchase #5	$106.60	4.602%	$111.5057	$111.51	$111.50	$111.50
Purchase #6	$97.43	4.137%	$101.4607	$101.46	$101.45	$101.50
Purchase #7	$81.43	7.405%	$87.4599	$87.46	$87.45	$87.50
7 purchase totals =	$961.43		$1,019.7308	$1,019.74	$1,019.70	$1,019.80