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	$98.96	9.609%	$108.4691	$108.47	$108.45	$108.50
Purchase #2	$105.66	10.243%	$116.4828	$116.48	$116.50	$116.50
Purchase #3	$52.86	4.559%	$55.2699	$55.27	$55.25	$55.30
Purchase #4	$82.43	3.788%	$85.5524	$85.55	$85.55	$85.60
Purchase #5	$242.44	13.320%	$274.733	$274.73	$274.75	$274.70
Purchase #6	$126.44	8.697%	$137.4365	$137.44	$137.45	$137.40
Purchase #7	$226.78	5.431%	$239.0964	$239.10	$239.10	$239.10
7 purchase totals =	$935.57		$1,017.0401	$1,017.04	$1,017.05	$1,017.10