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	$103.32	9.147%	$112.7707	$112.77	$112.75	$112.80
Purchase #2	$142.51	12.635%	$160.5161	$160.52	$160.50	$160.50
Purchase #3	$250.39	4.622%	$261.963	$261.96	$261.95	$262.00
Purchase #4	$34.55	10.652%	$38.2303	$38.23	$38.25	$38.20
Purchase #5	$108.93	7.149%	$116.7174	$116.72	$116.70	$116.70
Purchase #6	$92.90	11.321%	$103.4172	$103.42	$103.40	$103.40
Purchase #7	$201.72	10.665%	$223.2334	$223.23	$223.25	$223.20
7 purchase totals =	$934.32		$1,016.8481	$1,016.85	$1,016.80	$1,016.80