Quote from achilles28:
1) 10-20%
2) Same as any State or Sales tax already in place - for example, 15% on sticker price at the register for all end-consumer goods and services. In your example, Walmart would charge 15% on 50$ dollars. 15% of 50 cents (import price of glasses) is considered an import tariff or customs duty and something altogether different than a consumption tax.
3) Why would a sales tax be applied to wages? A consumption tax is only applied to end-consumer goods and services - a haircut, electronics, car wash, a guitar lesson, a new pair of shoes, a car etc. The point of the consumption tax is to get rid of the income tax and only tax purchases instead of income. Exemptions would be the same as they are now for homes, interest, (maybe) insurance.