Final answer:
The rule for total current in a parallel circuit is Kirchhoff's junction rule, which states that the sum of currents entering a junction must equal the sum of currents leaving it.
Step-by-step explanation:
The rule that pertains to the total current in a parallel circuit is Kirchhoff's first rule, also known as the junction rule. According to this rule, the sum of all currents entering a junction must equal the sum of all currents leaving the junction. This is consistent with the law of conservation of charge. In a parallel circuit, multiple paths for the current are present, and each path has its own current. If we express the total current as I and the currents in the individual branches as I1, I2, I3, ..., In, then the total current flowing into the junction (and hence the circuit) can be found by summing the currents in the branches: I = I1 + I2 + I3 + ... + In.