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	$118.34	7.377%	$127.0699	$127.07	$127.05	$127.10
Purchase #2	$51.97	7.712%	$55.9779	$55.98	$56.00	$56.00
Purchase #3	$13.96	11.221%	$15.5265	$15.53	$15.55	$15.50
Purchase #4	$170.54	6.385%	$181.429	$181.43	$181.45	$181.40
Purchase #5	$198.54	9.490%	$217.3814	$217.38	$217.40	$217.40
Purchase #6	$157.85	6.668%	$168.3754	$168.38	$168.40	$168.40
Purchase #7	$145.33	6.259%	$154.4262	$154.43	$154.45	$154.40
7 purchase totals =	$856.53		$920.1863	$920.20	$920.30	$920.20