minute trend returning inaccurate sample rate

Minute trend sample rates appear to be showing round-off/type cast errors. The sample rate should be 1/60 = 0.01666666.... The rate being returned is different, and seems to vary, presumably due to round-off errors. Here's an example rate: 1/0.016666699200868607 = 59.99988287710165 The sample rate should be set statically to 1/60 to floating point precision.