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	$216.84	7.302%	$232.6737	$232.67	$232.65	$232.70
Purchase #2	$200.77	9.255%	$219.3513	$219.35	$219.35	$219.40
Purchase #3	$74.31	6.105%	$78.8466	$78.85	$78.85	$78.80
Purchase #4	$198.77	9.412%	$217.4782	$217.48	$217.50	$217.50
Purchase #5	$105.81	3.493%	$109.5059	$109.51	$109.50	$109.50
Purchase #6	$97.70	3.299%	$100.9231	$100.92	$100.90	$100.90
Purchase #7	$195.44	7.434%	$209.969	$209.97	$209.95	$210.00
7 purchase totals =	$1,089.64		$1,168.7478	$1,168.75	$1,168.70	$1,168.80