How can I add an amount random error to a numerical variable in R?

I am working on investigating the relationship between body measurements and overall weight in a set of biological specimens using regression equations. I have been comparing my results to previous studies, which did not draw their measurement data and body weights from the same series of individuals. Instead, these studies used the mean values reported for each species from the previously published literature (with body measurements and weight drawn from different sets of individuals) or just took the midpoint of reported ranges of body measurements.

I am trying to figure out how to introduce a small amount of random error in my data to simulate the effects of drawing measurement and weight data from different sources. For example, mutating all data to be slightly altered from their actual value by roughly +/- 5% of their actual value, which is close to the difference I get between my measurements and the literature measurements, and seeing how much that affects accuracy statistics. I know there is the jitter() command, but that only seems to work with plotting data.