The six who completed their deals are pitcher Ian McKinney (fifth round), pitcher Jimmy Reed (sixth round), shortstop Chris Rivera (seventh round), outfielder Devante Lacy (24th round), pitcher Blake McKnight (38th round) and pitcher Kevin Herget (39th round).
Gonzales, taken with the 19th overall pick, has agreed to a signing bonus of $1.85 million, slightly below the slot value ($2.0558 million) assigned to that pick. Kaminsky, the 28th overall selection, is set to sign for $1.7853 million.
The Cardinals lured Mercado from his commitment to Florida State by giving him a higher-than-slot signing bonus of $1.5 million. The value assigned to the 57th overall pick had been $971,400.
Those signing bonuses total $5.1353 million, all of which counts against the Cardinals' pool of $6.9079 million to spend on players taken in the first 10 rounds. The money committed to players already signed from those rounds -- McKinney, Reed, Rivera and ninth-rounder Nick Petree -- was not immediately known, though it, too, must be accounted for in that pool.
Whatever pool money remains can be allocated to the four still-unsigned players from the first 10 rounds, as well as anyone taken later who receives a bonus of more than $100,000. Any spending overage will result in a financial tax or, if excessive enough, the loss of a future Draft pick.
Gonzales was considered one of the most advanced college pitchers available this year after going 7-3 with a 2.80 ERA in 16 starts (17 appearances) for Gonzaga as a junior. He struck out 96 in 106 innings.
Already possessing an above-average changeup, he is projected to move quickly through the system.
Kaminsky, 18, was taken out of St. Joseph's Regional High School in Montvale, N.J., after he completed a dominant senior season. He went 9-0 and struck out 118 while walking just five in 58 innings. The Cardinals used their extra first-round pick -- earned as compensation after the departure of free agent Kyle Lohse -- to take Kaminsky 28th overall.
Mercado, also 18, was taken with St. Louis' second-round pick. The highly touted defensive shortstop out of Vivian Gaither High School in Tampa, Fla., projects to remain at shortstop for the long term. The Cards also believe there is more to his bat than he showed while hitting .286 with five extra-base hits during his senior season.