5.5 cents is good.
0.55 dollars or 55 cents
55.5 cents.
55.5 cents or $.555
55% = 0.55 as a decimal. And there is really no simplest form for decimals.
0.055
0.55
55/100 is 55 in decimal form.
.55
55/100:= 55 ÷ 100= 0.55 in decimal
55 dollars and 3.6 cents
0.55
55% = 0.55