. . "ral Laws, and .385 per cent of the sales price of purchases, as defined by chapter 64I of the General Laws, from that portion of the taxes imposed under said chapters 64H and 64I as excises upon the sale and use at retail of tangible property or of services, and upon the storage, use or other consumption of tangible property, or of services, including interest thereon or penalties, but not includi" . .