According to Lilian Pi?eyro, supervisor of Migration at the Las Americas Airport if your foreign passport states that you were born in the Dominican Republic you will have no problems. You do not need to purchase a return ticket because the foreign passport indicating you are born here will be proof that you are Dominican.
While foreigners that are not Dominican nationals need to arrive with their return ticket, Marta Garcia, an inspector at Las Americas, said that at the present time they are not enforcing the requirement. That is, those arriving without a return ticket, may just be waved through, or the inspector will not even notice, since she says this is very unusual.
This is unusual because the airline will usually not board you if you do not have your return ticket or can prove you are Dominican. In case the "tourist" came without the return ticket, from past knowledge, would suppose you may be required to required to purchase a return ticket in order to enter the country. The cheapest one to buy would be a return to Puerto Rico. Another way to get around it is to purchase a ticket that has no restrictions and, in agreement with the travel agency, return this to the agency, for which there will not be a penalty.