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	$131.87	10.610%	$145.8614	$145.86	$145.85	$145.90
Purchase #2	$131.25	9.637%	$143.8986	$143.90	$143.90	$143.90
Purchase #3	$109.95	10.858%	$121.8884	$121.89	$121.90	$121.90
Purchase #4	$17.61	5.203%	$18.5262	$18.53	$18.55	$18.50
Purchase #5	$34.84	7.839%	$37.5711	$37.57	$37.55	$37.60
Purchase #6	$136.47	10.247%	$150.4541	$150.45	$150.45	$150.50
Purchase #7	$236.43	5.214%	$248.7575	$248.76	$248.75	$248.80
7 purchase totals =	$798.42		$866.9573	$866.96	$866.95	$867.10