you will need to create a separate shipping rule for each total range, for example:
Name: 1 cent - 50
Triggers:
Taxable total For the cart:
If the taxable total price for the cart is '>=" a value of '0.01'
AND
Taxable total For the cart:
If the taxable total price for the cart is '=" a value of '50'
Calculation:
Flat Rate charge of '1'
the same triggers and calculation will apply to the other rules, just changing the floor, ceiling and flat rate values.