Python rounding of random floats to nearest points on a 2D mesh grid

Despite numpy & scipy's many rounding functions, I cannot find one that allows me to discretize randomized floats with respect to nodes in a 2D mesh grid. For example,

# create mesh grid
n = 11
l = 8
x = np.linspace(0., l, n)
y = np.linspace(0., l, n)
xx, yy = np.meshgrid(x, y, sparse=True)

>>> xx
array([[ 0. ,  0.8,  1.6,  2.4,  3.2,  4. ,  4.8,  5.6,  6.4,  7.2,  8. ]])
>>> yy
array([[ 0. ],
   [ 0.8],
   [ 1.6],
   [ 2.4],
   [ 3.2],
   [ 4. ],
   [ 4.8],
   [ 5.6],
   [ 6.4],
   [ 7.2],
   [ 8. ]])

If I have m number of random float a=np.random.random((m,2))*l, how can I round them to the nearest mesh nodes?