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	$212.69	3.389%	$219.8981	$219.90	$219.90	$219.90
Purchase #2	$42.90	5.758%	$45.3702	$45.37	$45.35	$45.40
Purchase #3	$234.99	13.141%	$265.87	$265.87	$265.85	$265.90
Purchase #4	$237.51	3.760%	$246.4404	$246.44	$246.45	$246.40
Purchase #5	$57.59	5.123%	$60.5403	$60.54	$60.55	$60.50
Purchase #6	$119.28	11.835%	$133.3968	$133.40	$133.40	$133.40
Purchase #7	$40.49	6.128%	$42.9712	$42.97	$42.95	$43.00
7 purchase totals =	$945.45		$1,014.4870	$1,014.49	$1,014.45	$1,014.50