Based on the given feature and task, the relationship between the Repetition feature and the grain yield of the soybean cultivar can be analyzed using prior knowledge about soybean cultivation. Here, the Repetition feature refers to the number of times a particular experiment or measurement has been repeated for a given cultivar.

Analysis of Relationship:
In general, when it comes to measuring and analyzing agricultural variables like grain yield, higher repetition values tend to provide more accurate and reliable results. This is mainly because repeated experiments help minimize the impact of random variability and increase the precision of the data collected. Therefore, it is likely that higher Repetition values would be associated with higher grain yield for the soybean cultivar, while lower Repetition values may be related to lower grain yield.

To generate the requested dictionary, we need to provide 5 typical Repetition values for each target class ('low' and 'high').

```json
{
	"low": [1.0, 2.0, 3.0, 4.0, 5.0],
	"high": [6.0, 7.0, 8.0, 9.0, 10.0]
}
```

Please note that the Repetition values in the dictionary are provided as floats in lists, representing typical values for each target class.