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	$140.66	3.460%	$145.5268	$145.53	$145.55	$145.50
Purchase #2	$10.46	13.611%	$11.8837	$11.88	$11.90	$11.90
Purchase #3	$238.84	7.137%	$255.886	$255.89	$255.90	$255.90
Purchase #4	$196.90	8.846%	$214.3178	$214.32	$214.30	$214.30
Purchase #5	$93.83	12.521%	$105.5785	$105.58	$105.60	$105.60
Purchase #6	$208.50	12.684%	$234.9461	$234.95	$234.95	$234.90
Purchase #7	$93.28	5.663%	$98.5624	$98.56	$98.55	$98.60
7 purchase totals =	$982.47		$1,066.7013	$1,066.71	$1,066.75	$1,066.70