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	$43.37	7.735%	$46.7247	$46.72	$46.70	$46.70
Purchase #2	$205.28	8.856%	$223.4596	$223.46	$223.45	$223.50
Purchase #3	$92.50	10.659%	$102.3596	$102.36	$102.35	$102.40
Purchase #4	$100.81	8.379%	$109.2569	$109.26	$109.25	$109.30
Purchase #5	$78.83	9.243%	$86.1163	$86.12	$86.10	$86.10
Purchase #6	$231.54	6.458%	$246.4929	$246.49	$246.50	$246.50
Purchase #7	$118.57	6.769%	$126.596	$126.60	$126.60	$126.60
7 purchase totals =	$870.90		$941.0060	$941.01	$940.95	$941.10