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	$59.82	4.377%	$62.4383	$62.44	$62.45	$62.40
Purchase #2	$56.80	9.741%	$62.3329	$62.33	$62.35	$62.30
Purchase #3	$196.89	10.870%	$218.2919	$218.29	$218.30	$218.30
Purchase #4	$250.46	4.690%	$262.2066	$262.21	$262.20	$262.20
Purchase #5	$59.73	11.140%	$66.3839	$66.38	$66.40	$66.40
Purchase #6	$57.37	4.121%	$59.7342	$59.73	$59.75	$59.70
Purchase #7	$189.60	13.757%	$215.6833	$215.68	$215.70	$215.70
7 purchase totals =	$870.67		$947.0711	$947.06	$947.15	$947.00