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	$62.58	3.120%	$64.5325	$64.53	$64.55	$64.50
Purchase #2	$20.27	4.334%	$21.1485	$21.15	$21.15	$21.10
Purchase #3	$83.78	12.454%	$94.214	$94.21	$94.20	$94.20
Purchase #4	$162.28	8.732%	$176.4503	$176.45	$176.45	$176.50
Purchase #5	$27.59	13.725%	$31.3767	$31.38	$31.40	$31.40
Purchase #6	$90.65	12.172%	$101.6839	$101.68	$101.70	$101.70
Purchase #7	$50.39	3.255%	$52.0302	$52.03	$52.05	$52.00
7 purchase totals =	$497.54		$541.4361	$541.43	$541.50	$541.40