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	$96.32	11.222%	$107.129	$107.13	$107.15	$107.10
Purchase #2	$50.47	4.357%	$52.669	$52.67	$52.65	$52.70
Purchase #3	$139.49	5.605%	$147.3084	$147.31	$147.30	$147.30
Purchase #4	$112.44	12.244%	$126.2072	$126.21	$126.20	$126.20
Purchase #5	$66.43	9.696%	$72.8711	$72.87	$72.85	$72.90
Purchase #6	$65.25	6.583%	$69.5454	$69.55	$69.55	$69.50
Purchase #7	$127.42	11.560%	$142.1498	$142.15	$142.15	$142.10
7 purchase totals =	$657.82		$717.8799	$717.89	$717.85	$717.80