I don't6 know if anyone else suggested this but... You can use the assign method to call the recalc like this

Imported::Assign
lparameter lxnewval
this.imported = lxnewval
thisform.recalc()
return

...

CostoUnit::Assign
lparameter lxnewval
this.CostoUnit = lxnewval
thisform.recalc()
return

>Thank you all. This tip is great!
>
>Vin you're right about this:
>PPS: it might be quicker to sum those fields all at once:
>SUM importedd TO xImpDD, costounit TO xCostoUnit, costot TO xCosTot, costoumn TO xCostoUMN, costotmn TO xCosTotMN...
>
>but the correct sintaxis would be
>
>SUM value1, value2, value3 TO var1, var2, var3
>
>The first sintaxis gave me an error message.