TurboTax calculates your tax return based on the instructions on the CRA forms. In the case of the Tuition, Education and Textbook Amounts, the federal form used is Schedule 11, with most provinces having an equivalent form.
The education amount tax credit and the textbook tax credit are based on the length of time you attended school, not on the actual amounts you spent. You get a certain amount per month that you were in school, with full-time months earning a higher amount than part-time months.
Be aware that the education amount and the textbook credit are no longer available at the Federal level. Many provinces have also eliminated the education amount, and only Nunavut still has the textbook credit.
The Federal tuition credit is calculated by adding together all eligible tuition fees, then multiplying the amount by the lowest federal tax rate percentage for the current tax year. Ex: in the 2019 the lowest federal tax rate is 15%. So, a student paying tuition fees of $2,000 would be eligible for a tax credit of $300. The provincial credits are calculated in a similar way, but not all provinces have a tuition credit.
FYI: The credits for tuition, education and textbook amounts are non-refundable tax credits. This means that they can only be used to reduce taxes owing, and can’t generate a refund.
If you have TurboTax Live Assist & Review, here is how to talk to a Tax Expert: https://turbotax.community.intuit.ca/community/navigating-turbotax/help/i-m-using-turbotax-live-assist-review-how-do-i-talk-to-a-tax-expert/00/873764