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	$53.64	10.156%	$59.0877	$59.09	$59.10	$59.10
Purchase #2	$57.61	13.253%	$65.2451	$65.25	$65.25	$65.20
Purchase #3	$164.76	13.176%	$186.4688	$186.47	$186.45	$186.50
Purchase #4	$178.45	13.617%	$202.7495	$202.75	$202.75	$202.70
Purchase #5	$197.59	12.354%	$222.0003	$222.00	$222.00	$222.00
Purchase #6	$126.72	4.541%	$132.4744	$132.47	$132.45	$132.50
Purchase #7	$183.99	3.378%	$190.2052	$190.21	$190.20	$190.20
7 purchase totals =	$962.76		$1,058.2310	$1,058.24	$1,058.20	$1,058.20