If customer orders a 'Product A', offer them 'Ground', '2nd Day', or 'International' ($10.50, $20.50, $75.00 respectively). Multiply the shipping price times the number of units.
If customer orders a 'Product A' and a 'Product B', add $1.10 per 'Product B' to the shipping options.
If a customer orders just 'Product B', offer 'Ground USA' only, at $1.10 per unit.
If a customer ships to Ohio, add OH tax. If a customer ships to Florida, add FL tax. Tax on shipping.
Change credit card months to numeric codes. (i.e. replace February with 02, etc).