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	$126.60	5.869%	$134.0302	$134.03	$134.05	$134.00
Purchase #2	$197.89	7.847%	$213.4184	$213.42	$213.40	$213.40
Purchase #3	$101.89	9.299%	$111.3648	$111.36	$111.35	$111.40
Purchase #4	$32.81	8.518%	$35.6048	$35.60	$35.60	$35.60
Purchase #5	$188.27	3.619%	$195.0835	$195.08	$195.10	$195.10
Purchase #6	$37.59	5.588%	$39.6905	$39.69	$39.70	$39.70
Purchase #7	$179.75	9.522%	$196.8658	$196.87	$196.85	$196.90
7 purchase totals =	$864.80		$926.0580	$926.05	$926.05	$926.10