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	$99.39	8.252%	$107.5917	$107.59	$107.60	$107.60
Purchase #2	$33.62	11.695%	$37.5519	$37.55	$37.55	$37.60
Purchase #3	$245.30	4.219%	$255.6492	$255.65	$255.65	$255.60
Purchase #4	$46.88	11.739%	$52.3832	$52.38	$52.40	$52.40
Purchase #5	$83.61	4.531%	$87.3984	$87.40	$87.40	$87.40
Purchase #6	$162.27	5.785%	$171.6573	$171.66	$171.65	$171.70
Purchase #7	$30.39	7.832%	$32.7701	$32.77	$32.75	$32.80
7 purchase totals =	$701.46		$745.0018	$745.00	$745.00	$745.10