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	$193.48	3.854%	$200.9367	$200.94	$200.95	$200.90
Purchase #2	$77.50	3.866%	$80.4962	$80.50	$80.50	$80.50
Purchase #3	$164.38	5.103%	$172.7683	$172.77	$172.75	$172.80
Purchase #4	$107.56	8.215%	$116.3961	$116.40	$116.40	$116.40
Purchase #5	$250.42	12.431%	$281.5497	$281.55	$281.55	$281.50
Purchase #6	$39.41	6.243%	$41.8704	$41.87	$41.85	$41.90
Purchase #7	$99.89	13.561%	$113.4361	$113.44	$113.45	$113.40
7 purchase totals =	$932.64		$1,007.4535	$1,007.47	$1,007.45	$1,007.40