When I took my OW and AOW in 1985, we used the older PADI table that was essentially a rebranded US Navy table. The US Navy table is very liberal by modern standards and was not really intended to be used for repetetive diving in US Navy service so it was common to round "up" to the next greatest time and next greatest depth. You also planned the deco/NDL limits using square profiles at the deepest depth while religeously avoiding actually diving a square profile at that depth in order to create a healthy fudge factor.
For a cold water dive or strenous dive, we were taught to round up to the next greatest depth and for a strenuous dive in cold water we were instructed to round up to the next greatest depth AND time.
Newer tables are more conservative, but it is still prudent to round to the next greatest depth to accommodate the potential for reduces circulation and offgassing in colder water. And I'd define a "cold water" dive as any dive where you get at all chilled.
For a cold water dive or strenous dive, we were taught to round up to the next greatest depth and for a strenuous dive in cold water we were instructed to round up to the next greatest depth AND time.
Newer tables are more conservative, but it is still prudent to round to the next greatest depth to accommodate the potential for reduces circulation and offgassing in colder water. And I'd define a "cold water" dive as any dive where you get at all chilled.