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	$55.55	10.730%	$61.5105	$61.51	$61.50	$61.50
Purchase #2	$70.46	4.628%	$73.7209	$73.72	$73.70	$73.70
Purchase #3	$6.30	3.499%	$6.5204	$6.52	$6.50	$6.50
Purchase #4	$63.93	12.206%	$71.7333	$71.73	$71.75	$71.70
Purchase #5	$102.37	9.440%	$112.0337	$112.03	$112.05	$112.00
Purchase #6	$227.62	11.536%	$253.8782	$253.88	$253.90	$253.90
Purchase #7	$196.81	10.249%	$216.9811	$216.98	$217.00	$217.00
7 purchase totals =	$723.04		$796.3781	$796.37	$796.40	$796.30