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	$234.96	7.863%	$253.4349	$253.43	$253.45	$253.40
Purchase #2	$78.86	7.506%	$84.7792	$84.78	$84.80	$84.80
Purchase #3	$143.56	4.585%	$150.1422	$150.14	$150.15	$150.10
Purchase #4	$139.47	13.652%	$158.5104	$158.51	$158.50	$158.50
Purchase #5	$131.59	13.172%	$148.923	$148.92	$148.90	$148.90
Purchase #6	$8.80	5.708%	$9.3023	$9.30	$9.30	$9.30
Purchase #7	$191.72	10.404%	$211.6665	$211.67	$211.65	$211.70
7 purchase totals =	$928.96		$1,016.7585	$1,016.75	$1,016.75	$1,016.70