The imposition of taxes and the application of tax rates do not depend upon the business in which the taxpayer is primarily engaged. One business may be subject to two or more tax rates. If a business is within the purview of two or more of the paragraphs of § 237-13 or other provisions of this chapter all of them apply, each provision being applicable to the appropriate item of gross income, gross proceeds of sales, or value of products. However, any person engaging or continuing in a business having gross income, gross proceeds of sales, and value of products, or any of these as the case may be, taxable at different rates, shall be subject to taxation upon the aggregate amount of the gross income, gross proceeds of sales, and value of products of the business at the highest rate applicable to any part of the aggregate, unless the person shall segregate the parts taxable at different rates upon the person’s records and in the person’s returns, and shall sustain the burden of proving that the segregation was correctly made.