Resolution Class

public with sharing class TaxServiceExtensionResolverSample extends commercestoretax.TaxService implements CommerceExtension.ResolutionStrategy {
    public CommerceExtension.Resolution resolve() {
        // The Sample Extension Provider registered with developer name as 'tax_extension_provider_for_us' will be selected for execution for en_US locale
        if(CommerceExtension.ExtensionInfo.getLocaleString() == 'en_US') {
            return new CommerceExtension.Resolution('tax_extension_provider_for_us');
        }
        // The Sample Extension Provider registered with developer name as 'tax_extension_provider_for_canada' will be selected for execution for en_CA locale
        if(CommerceExtension.ExtensionInfo.getLocaleString() == 'en_CA') {
            return new CommerceExtension.Resolution('tax_extension_provider_for_canada');
        }
        // The default Salesforce Internal Tax Api will return an empty response for German locale
        if(CommerceExtension.ExtensionInfo.getLocaleString() == 'de') {
            return new CommerceExtension.Resolution(CommerceExtension.ResolutionStates.OFF);
        }
        // The default Salesforce Internal Tax Api will be selected for execution for all other locales than US, Canada and Germany
        return new CommerceExtension.Resolution();
    }
}