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	$119.43	10.706%	$132.2162	$132.22	$132.20	$132.20
Purchase #2	$200.94	11.229%	$223.5036	$223.50	$223.50	$223.50
Purchase #3	$229.37	4.761%	$240.2903	$240.29	$240.30	$240.30
Purchase #4	$14.40	6.505%	$15.3367	$15.34	$15.35	$15.30
Purchase #5	$5.39	6.162%	$5.7221	$5.72	$5.70	$5.70
Purchase #6	$63.66	5.735%	$67.3109	$67.31	$67.30	$67.30
Purchase #7	$27.52	13.724%	$31.2968	$31.30	$31.30	$31.30
7 purchase totals =	$660.71		$715.6766	$715.68	$715.65	$715.60