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	$119.83	4.270%	$124.9467	$124.95	$124.95	$124.90
Purchase #2	$63.75	13.146%	$72.1306	$72.13	$72.15	$72.10
Purchase #3	$223.75	9.718%	$245.494	$245.49	$245.50	$245.50
Purchase #4	$52.51	4.790%	$55.0252	$55.03	$55.05	$55.00
Purchase #5	$164.49	5.721%	$173.9005	$173.90	$173.90	$173.90
Purchase #6	$10.49	11.380%	$11.6838	$11.68	$11.70	$11.70
Purchase #7	$75.45	13.166%	$85.3837	$85.38	$85.40	$85.40
7 purchase totals =	$710.27		$768.5645	$768.56	$768.65	$768.50