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	$219.31	4.437%	$229.0408	$229.04	$229.05	$229.00
Purchase #2	$228.30	7.687%	$245.8494	$245.85	$245.85	$245.80
Purchase #3	$52.79	13.634%	$59.9874	$59.99	$60.00	$60.00
Purchase #4	$35.32	3.311%	$36.4894	$36.49	$36.50	$36.50
Purchase #5	$105.53	8.536%	$114.538	$114.54	$114.55	$114.50
Purchase #6	$230.39	12.800%	$259.8799	$259.88	$259.90	$259.90
Purchase #7	$92.65	13.417%	$105.0809	$105.08	$105.10	$105.10
7 purchase totals =	$964.29		$1,050.8658	$1,050.87	$1,050.95	$1,050.80