f[x_, signbits_, integerbits_, fractionbits_]

data = {0.0000618365, 0.0000701533, -0.0000747471, 0.0000595436, 0.0000705533,
0.0000728675, 0.0000711056, 0.0000684559, 0.0000753624, -0.0000557638}

<< ComputerArithmetic`

(*Set Math Parameters*)

SetArithmetic[6, 10, ExponentRange -> {-20, 20}];

fpConvert[x_, integerbits_, fractionbits_] := ComputerNumber[IntegerPart[x] + Round[FractionalPart[x], 2^-fractionbits]];

N[fpConvert[Pi, 3, 2], {8, 8}]
N[fpConvert[Pi, 3, 4], {8, 8}]
N[fpConvert[Pi, 3, 8], {8, 8}]
N[fpConvert[Pi, 3, 13], {8, 8}]