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	$156.60	9.752%	$171.8716	$171.87	$171.85	$171.90
Purchase #2	$199.46	13.249%	$225.8865	$225.89	$225.90	$225.90
Purchase #3	$172.96	3.708%	$179.3734	$179.37	$179.35	$179.40
Purchase #4	$91.95	10.424%	$101.5349	$101.53	$101.55	$101.50
Purchase #5	$58.30	13.798%	$66.3442	$66.34	$66.35	$66.30
Purchase #6	$81.35	5.131%	$85.5241	$85.52	$85.50	$85.50
Purchase #7	$193.97	3.868%	$201.4728	$201.47	$201.45	$201.50
7 purchase totals =	$954.59		$1,032.0075	$1,031.99	$1,031.95	$1,032.00