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	$167.98	4.825%	$176.085	$176.09	$176.10	$176.10
Purchase #2	$154.64	8.691%	$168.0798	$168.08	$168.10	$168.10
Purchase #3	$168.46	8.518%	$182.8094	$182.81	$182.80	$182.80
Purchase #4	$105.98	5.445%	$111.7506	$111.75	$111.75	$111.80
Purchase #5	$101.50	8.319%	$109.9438	$109.94	$109.95	$109.90
Purchase #6	$149.50	13.593%	$169.8215	$169.82	$169.80	$169.80
Purchase #7	$104.35	11.732%	$116.5923	$116.59	$116.60	$116.60
7 purchase totals =	$952.41		$1,035.0824	$1,035.08	$1,035.10	$1,035.10