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	$117.59	7.854%	$126.8255	$126.83	$126.85	$126.80
Purchase #2	$107.35	11.573%	$119.7736	$119.77	$119.75	$119.80
Purchase #3	$43.71	4.483%	$45.6695	$45.67	$45.65	$45.70
Purchase #4	$191.67	6.776%	$204.6576	$204.66	$204.65	$204.70
Purchase #5	$125.55	4.658%	$131.3981	$131.40	$131.40	$131.40
Purchase #6	$95.55	10.781%	$105.8512	$105.85	$105.85	$105.90
Purchase #7	$178.74	3.626%	$185.2211	$185.22	$185.20	$185.20
7 purchase totals =	$860.16		$919.3966	$919.40	$919.35	$919.50