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	$207.35	3.373%	$214.3439	$214.34	$214.35	$214.30
Purchase #2	$52.38	4.792%	$54.89	$54.89	$54.90	$54.90
Purchase #3	$15.79	4.684%	$16.5296	$16.53	$16.55	$16.50
Purchase #4	$14.41	13.171%	$16.3079	$16.31	$16.30	$16.30
Purchase #5	$111.49	7.503%	$119.8551	$119.86	$119.85	$119.90
Purchase #6	$111.32	7.686%	$119.8761	$119.88	$119.90	$119.90
Purchase #7	$55.47	12.596%	$62.457	$62.46	$62.45	$62.50
7 purchase totals =	$568.21		$604.2596	$604.27	$604.30	$604.30