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	$40.66	10.592%	$44.9667	$44.97	$44.95	$45.00
Purchase #2	$149.70	4.842%	$156.9485	$156.95	$156.95	$156.90
Purchase #3	$240.43	3.674%	$249.2634	$249.26	$249.25	$249.30
Purchase #4	$151.27	3.533%	$156.6144	$156.61	$156.60	$156.60
Purchase #5	$14.56	7.292%	$15.6217	$15.62	$15.60	$15.60
Purchase #6	$32.46	3.303%	$33.5322	$33.53	$33.55	$33.50
Purchase #7	$52.30	10.114%	$57.5896	$57.59	$57.60	$57.60
7 purchase totals =	$681.38		$714.5365	$714.53	$714.50	$714.50