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	$105.60	8.394%	$114.4641	$114.46	$114.45	$114.50
Purchase #2	$241.86	3.836%	$251.1377	$251.14	$251.15	$251.10
Purchase #3	$171.90	11.724%	$192.0536	$192.05	$192.05	$192.10
Purchase #4	$195.85	13.555%	$222.3975	$222.40	$222.40	$222.40
Purchase #5	$32.54	7.265%	$34.904	$34.90	$34.90	$34.90
Purchase #6	$66.61	8.678%	$72.3904	$72.39	$72.40	$72.40
Purchase #7	$218.53	4.165%	$227.6318	$227.63	$227.65	$227.60
7 purchase totals =	$1,032.89		$1,114.9791	$1,114.97	$1,115.00	$1,115.00