I got 4100. Not sure why people would think it's 5000.

1000 + 40 = 1040
1040 + 1000 = 2040
2040 30 = 2070
2070 + 1000 = 3070
3070 + 20 = 3090
3090 + 1000 = 4090
4090 + 10 = 4100