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	$114.74	10.544%	$126.8382	$126.84	$126.85	$126.80
Purchase #2	$112.44	9.812%	$123.4726	$123.47	$123.45	$123.50
Purchase #3	$175.76	5.689%	$185.759	$185.76	$185.75	$185.80
Purchase #4	$61.85	7.612%	$66.558	$66.56	$66.55	$66.60
Purchase #5	$51.25	9.682%	$56.212	$56.21	$56.20	$56.20
Purchase #6	$58.72	5.602%	$62.0095	$62.01	$62.00	$62.00
Purchase #7	$66.89	10.303%	$73.7817	$73.78	$73.80	$73.80
7 purchase totals =	$641.65		$694.6310	$694.63	$694.60	$694.70