No.
Basicaly you roll each attack seperatly:
ATTACKS
CHARACTERISTIC
The maximum number of attacks
that can be made by a weapon is
equal to its Attacks characteristic.
Make the attacks one at a time,
unless you are using the rules for
Multiple Attacks.
MULTIPLE ATTACKS
In order to resolve several attacks
at once, all of the attacks must be
made by models from the same unit,
with the same type of weapon, and
against the same target unit. If this
is the case, make all of the hit rolls at
the same time, then all of the wound
rolls, and finally all of the save rolls.
Doing them the same time does not mean that it is only 1 roll. You choose for each of your attacks (Attack Characteristic) seperatly.
Rerolling "failed" hitrolls follows the same rules.
Keep in mind, that you can only reroll unmodified rolls (before applying modifieres like rend etc.)