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	$12.45	11.224%	$13.8474	$13.85	$13.85	$13.80
Purchase #2	$67.93	6.387%	$72.2687	$72.27	$72.25	$72.30
Purchase #3	$72.86	4.698%	$76.283	$76.28	$76.30	$76.30
Purchase #4	$205.76	6.408%	$218.9451	$218.95	$218.95	$218.90
Purchase #5	$42.88	9.731%	$47.0527	$47.05	$47.05	$47.10
Purchase #6	$94.44	5.448%	$99.5851	$99.59	$99.60	$99.60
Purchase #7	$198.39	9.697%	$217.6279	$217.63	$217.65	$217.60
7 purchase totals =	$694.71		$745.6099	$745.62	$745.65	$745.60