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	$209.85	7.330%	$225.232	$225.23	$225.25	$225.20
Purchase #2	$41.82	8.192%	$45.2459	$45.25	$45.25	$45.20
Purchase #3	$87.42	12.733%	$98.5512	$98.55	$98.55	$98.60
Purchase #4	$79.60	7.841%	$85.8414	$85.84	$85.85	$85.80
Purchase #5	$176.48	6.268%	$187.5418	$187.54	$187.55	$187.50
Purchase #6	$52.97	11.641%	$59.1362	$59.14	$59.15	$59.10
Purchase #7	$61.40	3.403%	$63.4894	$63.49	$63.50	$63.50
7 purchase totals =	$709.54		$765.0379	$765.04	$765.10	$764.90