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	$39.32	11.479%	$43.8335	$43.83	$43.85	$43.80
Purchase #2	$95.75	4.819%	$100.3642	$100.36	$100.35	$100.40
Purchase #3	$115.92	7.538%	$124.658	$124.66	$124.65	$124.70
Purchase #4	$138.82	6.321%	$147.5948	$147.59	$147.60	$147.60
Purchase #5	$24.35	11.554%	$27.1634	$27.16	$27.15	$27.20
Purchase #6	$106.62	7.473%	$114.5877	$114.59	$114.60	$114.60
Purchase #7	$128.55	10.263%	$141.7431	$141.74	$141.75	$141.70
7 purchase totals =	$649.33		$699.9447	$699.93	$699.95	$700.00