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	$209.43	9.523%	$229.374	$229.37	$229.35	$229.40
Purchase #2	$66.95	5.671%	$70.7467	$70.75	$70.75	$70.70
Purchase #3	$133.41	11.256%	$148.4266	$148.43	$148.45	$148.40
Purchase #4	$109.91	12.590%	$123.7477	$123.75	$123.75	$123.70
Purchase #5	$89.98	9.416%	$98.4525	$98.45	$98.45	$98.50
Purchase #6	$196.78	9.546%	$215.5646	$215.56	$215.55	$215.60
Purchase #7	$114.96	13.599%	$130.5934	$130.59	$130.60	$130.60
7 purchase totals =	$921.42		$1,016.9055	$1,016.90	$1,016.90	$1,016.90