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	$145.73	11.662%	$162.725	$162.73	$162.75	$162.70
Purchase #2	$186.59	7.293%	$200.198	$200.20	$200.20	$200.20
Purchase #3	$237.27	6.571%	$252.861	$252.86	$252.85	$252.90
Purchase #4	$11.38	9.812%	$12.4966	$12.50	$12.50	$12.50
Purchase #5	$46.59	12.620%	$52.4697	$52.47	$52.45	$52.50
Purchase #6	$166.63	3.529%	$172.5104	$172.51	$172.50	$172.50
Purchase #7	$142.78	12.492%	$160.6161	$160.62	$160.60	$160.60
7 purchase totals =	$936.97		$1,013.8768	$1,013.89	$1,013.85	$1,013.90