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	$119.28	7.207%	$127.8765	$127.88	$127.90	$127.90
Purchase #2	$41.41	8.128%	$44.7758	$44.78	$44.80	$44.80
Purchase #3	$245.27	11.595%	$273.7091	$273.71	$273.70	$273.70
Purchase #4	$173.63	13.385%	$196.8704	$196.87	$196.85	$196.90
Purchase #5	$14.88	6.392%	$15.8311	$15.83	$15.85	$15.80
Purchase #6	$226.56	3.587%	$234.6867	$234.69	$234.70	$234.70
Purchase #7	$66.32	7.438%	$71.2529	$71.25	$71.25	$71.30
7 purchase totals =	$887.35		$965.0025	$965.01	$965.05	$965.10