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	$57.48	8.543%	$62.3905	$62.39	$62.40	$62.40
Purchase #2	$52.93	3.171%	$54.6084	$54.61	$54.60	$54.60
Purchase #3	$175.35	8.727%	$190.6528	$190.65	$190.65	$190.70
Purchase #4	$147.60	11.409%	$164.4397	$164.44	$164.45	$164.40
Purchase #5	$208.27	5.103%	$218.898	$218.90	$218.90	$218.90
Purchase #6	$232.42	3.284%	$240.0527	$240.05	$240.05	$240.10
Purchase #7	$105.42	5.588%	$111.3109	$111.31	$111.30	$111.30
7 purchase totals =	$979.47		$1,042.3530	$1,042.35	$1,042.35	$1,042.40