Maybe / maybe not. IF you want the vias to be the "same size" as the trace, vias for a 5 mil trace will have a "pretty small" hole size, it's unlikely that these will be manufactured with a regular mechanical drill so your fabrciation costs are going to be high. Equally, you will likely have a number of vias in the design, possibly a significant number, these are going to take up space on the board. So there is going to be a compromise between the size of the vias and the cost of manufacture. Fabricators will usually provide a list of "no cost" board parameters for their basic fabrication processing and additional costs that will be applicable beyond those parameters. You can get an estimate of the fabrication cost from these parameters and get an idea whether, or not, you are going to have to go beyond the "no cost" parameters to fabricate your board.