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	$155.88	13.808%	$177.4039	$177.40	$177.40	$177.40
Purchase #2	$162.56	3.717%	$168.6024	$168.60	$168.60	$168.60
Purchase #3	$199.94	10.870%	$221.6735	$221.67	$221.65	$221.70
Purchase #4	$119.59	10.808%	$132.5153	$132.52	$132.50	$132.50
Purchase #5	$61.61	6.265%	$65.4699	$65.47	$65.45	$65.50
Purchase #6	$43.70	4.382%	$45.6149	$45.61	$45.60	$45.60
Purchase #7	$194.50	10.213%	$214.3643	$214.36	$214.35	$214.40
7 purchase totals =	$937.78		$1,025.6442	$1,025.63	$1,025.55	$1,025.70