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	$196.26	9.802%	$215.4974	$215.50	$215.50	$215.50
Purchase #2	$55.90	6.746%	$59.671	$59.67	$59.65	$59.70
Purchase #3	$142.96	8.538%	$155.1659	$155.17	$155.15	$155.20
Purchase #4	$54.56	4.595%	$57.067	$57.07	$57.05	$57.10
Purchase #5	$86.29	10.695%	$95.5187	$95.52	$95.50	$95.50
Purchase #6	$240.47	13.181%	$272.1664	$272.17	$272.15	$272.20
Purchase #7	$128.55	11.306%	$143.0839	$143.08	$143.10	$143.10
7 purchase totals =	$904.99		$998.1703	$998.18	$998.10	$998.30