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	$196.39	9.758%	$215.5537	$215.55	$215.55	$215.60
Purchase #2	$225.29	13.196%	$255.0193	$255.02	$255.00	$255.00
Purchase #3	$85.70	7.132%	$91.8121	$91.81	$91.80	$91.80
Purchase #4	$99.89	8.641%	$108.5215	$108.52	$108.50	$108.50
Purchase #5	$62.35	6.585%	$66.4557	$66.46	$66.45	$66.50
Purchase #6	$12.79	3.200%	$13.1993	$13.20	$13.20	$13.20
Purchase #7	$249.68	4.719%	$261.4624	$261.46	$261.45	$261.50
7 purchase totals =	$932.09		$1,012.0240	$1,012.02	$1,011.95	$1,012.10