Lower limits: 5 - 0.5 = 4.5 \\text{ cm}, 6 - 0.5 = 5.5 \\text{ cm}, 3 - 0.5 = 2.5 \\text{ cm}. Volume = 4.5 \\times 5.5 \\times 3 = 73.875 \\text{ cm}^3. Upper limits: 5 + 0.5 = 5.5 \\text{ cm}, 6 + 0.5 = 6.5 \\text{ cm}, 3 + 0.5 = 3.5 \\text{ cm}. Volume = 5.5 \\times 6.5 \\times 3.5 = 134.875 \\text{ cm}^3.