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	$69.43	4.387%	$72.4759	$72.48	$72.50	$72.50
Purchase #2	$42.49	4.398%	$44.3587	$44.36	$44.35	$44.40
Purchase #3	$59.85	4.697%	$62.6612	$62.66	$62.65	$62.70
Purchase #4	$124.29	6.665%	$132.5739	$132.57	$132.55	$132.60
Purchase #5	$56.30	11.811%	$62.9496	$62.95	$62.95	$62.90
Purchase #6	$229.85	7.259%	$246.5348	$246.53	$246.55	$246.50
Purchase #7	$166.75	7.856%	$179.8499	$179.85	$179.85	$179.80
7 purchase totals =	$748.96		$801.4040	$801.40	$801.40	$801.40