Most bonuses do not stack with each other. Unnamed bonuses stack, unless from the same source. Dodge bonuses stack. Circumstance bonuses CAN stack, dependent on conditions and GM approval. Otherwise, no, bonuses of the same type do not stack. This is called out under the 'Bonus' entry, p. 11 of the Core Rulebook (CRB), and under 'Stacking', p. 12, CRB.