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	$196.35	8.858%	$213.7427	$213.74	$213.75	$213.70
Purchase #2	$191.27	10.326%	$211.0205	$211.02	$211.00	$211.00
Purchase #3	$74.84	8.529%	$81.2231	$81.22	$81.20	$81.20
Purchase #4	$94.34	11.756%	$105.4306	$105.43	$105.45	$105.40
Purchase #5	$98.93	6.600%	$105.4594	$105.46	$105.45	$105.50
Purchase #6	$69.31	12.651%	$78.0784	$78.08	$78.10	$78.10
Purchase #7	$138.65	7.181%	$148.6065	$148.61	$148.60	$148.60
7 purchase totals =	$863.69		$943.5612	$943.56	$943.55	$943.50