Big Business 3.0.0 added the Keyboard Shortcut:
Command - T to switch toolbars
hold the Ctrl (Win) or Apple (Mac) key and press the letter "t"
This previous keyboard command for switching toolbars was Command - F15, a key which is not available on all keyboards.
Typing Command - T switches you to the next Big Business toolbar.
"Feature Request 1) Add Command-Shift-T to cycle through the toolbars
backwards" (3694)
Shift-Command-T has been added in Big Business 3.0.2 to switch to the previous toolbar (in the toolbar pulldown or menu).