It depends.

A company such as you describe ("Product close to launch, series A finished, in a specialized field") might have 20 engineers building the project; or it might have 3 people and several million dollars of hardware. Obviously in the later case a new employee would make a greater impact on the company and thus be able to demand more options.

An engineer such as you describe ("engineer, 5 years experience") might be a 23 year old who got an entry-level programming job straight out of high school and has no particular expertise; or he might have a PhD and be a world-recognized expert in the particular specialized field in which the company is working. Obviously in the later case he would be able to demand more options.

All I can say with confidence based on the information given is that he should probably expect somewhere between 0.01% and 25%.

a tenth of a percent .001 to a quarter of a percent .0025 at best.

undefined