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Oh goody, at last something of Brexit interest in the Conservative leadership contest: Michael Gove's pledge to use "the opportunity of life outside the EU to look to replace VAT with a lower, simpler, sales tax" (Sky News, Daily Express, Sunday Telegraph, etc).
If Sales Tax means a tax on sales specifically to consumers, rather than on those to businesses as well (as is the case with VAT), then the question arises: when and where is the taxpoint? Presumably at the point of sale/purchase, and away from the border - making life simpler for imports across the Dover Straits and ILB. If one assumes that the tax only applies to sales to UK consumers, then exports become simpler too because they would be outside the scope of the tax and the physical point of export would (or at least should) have no significance.
The OAPs amongst us might call this Purchase Tax. I haven't spotted Mr Gove saying whether there will be more than one rate of tax though; perhaps 'simpler' means 'a uniform rate'... in which case you can expect an outcry when it is applied to food, infants' clothes and so on.