rand(1:10) vs Int(round(10*rand())

General Usage Performance
9

You might also have a look at this Julia snippets: Basics of generating random numbers in Julia (it is Julia 0.6 based but the reasons for the bias have not changed).

Having said that for very small N in very tight loops I use the approximate formula as the bias is small and it is significantly faster (see the corrected benchmark below - also you have to use 1+floor not ceil as ceil can produce 0):

julia> f1(N=5,M=10^6) = mean(iseven(1+floor(Int, N*rand())) for i in 1:M)
f1 (generic function with 3 methods)

julia> f2(N=5,M=10^6) = mean(iseven(rand(1:N)) for i in 1:M)
f2 (generic function with 3 methods)

julia> @btime f1()
  9.020 ms (0 allocations: 0 bytes)
0.400145

julia> @btime f2()
  17.681 ms (0 allocations: 0 bytes)
0.399574
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