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	$119.71	3.240%	$123.5886	$123.59	$123.60	$123.60
Purchase #2	$29.72	7.446%	$31.933	$31.93	$31.95	$31.90
Purchase #3	$202.62	12.427%	$227.7996	$227.80	$227.80	$227.80
Purchase #4	$135.42	11.709%	$151.2763	$151.28	$151.30	$151.30
Purchase #5	$248.98	12.732%	$280.6801	$280.68	$280.70	$280.70
Purchase #6	$84.30	3.833%	$87.5312	$87.53	$87.55	$87.50
Purchase #7	$104.32	8.583%	$113.2738	$113.27	$113.25	$113.30
7 purchase totals =	$925.07		$1,016.0826	$1,016.08	$1,016.15	$1,016.10