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	$126.40	4.182%	$131.686	$131.69	$131.70	$131.70
Purchase #2	$153.70	5.567%	$162.2565	$162.26	$162.25	$162.30
Purchase #3	$54.49	11.262%	$60.6267	$60.63	$60.65	$60.60
Purchase #4	$54.38	6.730%	$58.0398	$58.04	$58.05	$58.00
Purchase #5	$114.44	4.500%	$119.5898	$119.59	$119.60	$119.60
Purchase #6	$152.76	3.726%	$158.4518	$158.45	$158.45	$158.50
Purchase #7	$53.36	11.146%	$59.3075	$59.31	$59.30	$59.30
7 purchase totals =	$709.53		$749.9581	$749.97	$750.00	$750.00