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	$61.26	4.287%	$63.8862	$63.89	$63.90	$63.90
Purchase #2	$181.40	7.401%	$194.8254	$194.83	$194.85	$194.80
Purchase #3	$114.62	4.625%	$119.9212	$119.92	$119.90	$119.90
Purchase #4	$132.97	7.436%	$142.8576	$142.86	$142.85	$142.90
Purchase #5	$192.55	7.817%	$207.6016	$207.60	$207.60	$207.60
Purchase #6	$86.27	5.208%	$90.7629	$90.76	$90.75	$90.80
Purchase #7	$112.82	12.759%	$127.2147	$127.21	$127.20	$127.20
7 purchase totals =	$881.89		$947.0696	$947.07	$947.05	$947.10