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	$12.88	13.191%	$14.579	$14.58	$14.60	$14.60
Purchase #2	$35.73	4.663%	$37.3961	$37.40	$37.40	$37.40
Purchase #3	$158.94	9.515%	$174.0631	$174.06	$174.05	$174.10
Purchase #4	$146.83	3.806%	$152.4183	$152.42	$152.40	$152.40
Purchase #5	$85.56	13.657%	$97.2449	$97.24	$97.25	$97.20
Purchase #6	$212.48	13.838%	$241.883	$241.88	$241.90	$241.90
Purchase #7	$104.39	4.631%	$109.2243	$109.22	$109.20	$109.20
7 purchase totals =	$756.81		$826.8087	$826.80	$826.80	$826.80