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	$224.43	4.612%	$234.7807	$234.78	$234.80	$234.80
Purchase #2	$12.82	3.341%	$13.2483	$13.25	$13.25	$13.20
Purchase #3	$65.94	8.563%	$71.5864	$71.59	$71.60	$71.60
Purchase #4	$145.57	4.583%	$152.2415	$152.24	$152.25	$152.20
Purchase #5	$167.49	11.651%	$187.0043	$187.00	$187.00	$187.00
Purchase #6	$109.95	12.412%	$123.597	$123.60	$123.60	$123.60
Purchase #7	$118.82	11.336%	$132.2894	$132.29	$132.30	$132.30
7 purchase totals =	$845.02		$914.7476	$914.75	$914.80	$914.70