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	$148.81	10.389%	$164.2699	$164.27	$164.25	$164.30
Purchase #2	$16.78	11.194%	$18.6584	$18.66	$18.65	$18.70
Purchase #3	$63.34	13.522%	$71.9048	$71.90	$71.90	$71.90
Purchase #4	$87.68	13.798%	$99.7781	$99.78	$99.80	$99.80
Purchase #5	$73.57	7.256%	$78.9082	$78.91	$78.90	$78.90
Purchase #6	$133.71	6.108%	$141.877	$141.88	$141.90	$141.90
Purchase #7	$139.28	12.542%	$156.7485	$156.75	$156.75	$156.70
7 purchase totals =	$663.17		$732.1449	$732.15	$732.15	$732.20