How should I handle tax that is less than my denominator?

Hello I am a new solidity dev. In this tax function I am dividing by the simplifed fraction ex(5% =1/20 so I am doing amount/tax rate). My question is since I am deploying on a network with low gas how can I tax the buys under 20 tokens because solidity doesn't do decimals so all buy's under 20 tokens will go untaxed. I want the initial supply to be realativly small so I dont want make it 100 billion tokens. And I also dont want to just charge 1 token in tax for all buys under 20 tokens cause if tokens takes off then a ton of the supply will be burned so most of the buys will be under 20 tokens and that wont work either.

Was wondering if anyone had a solution ?

    uint taxAmt=amount/taxRate;
    uint transferAmt=amount-taxAmt;
    uint swapAmt=taxAmt/2;
    uint tokenTaxAmt=taxAmt-swapAmt;
    uint ethTaxAmt=swapTokensForETHAndSend(swapAmt,location);