If I recall correctly, 'same-day' cannot be entered in the online Calculator, when filing a Citizenship application. In other words, the system cannot calculat, for example, from June 30 to June 30, as 1 day. However, when an RQ is issued, I recall it asking for same-day trips to be also reported. You could perhaps add additional note listing all same-day trips, if there is a chance to avoid an RQ. You need not enter into Calculator.
However, you must show proof of such trips. In my case, for, e.g., I would have receipts for toll-tax (in/out), purchase receipt for the 'same-day' in Canada/USA, ATM receipts, fuel receipts or even duty-free, if purchased/allowed, 407 fees records, etc. Of these, Toll-receipts are likely the more reliable, as are 407 payment records. Entering on the 407 (coming from the Buffalo side) is convenient for me, at least. Those sorts of evidence, so far, came handy for me because CBSA (ATIP process) revealed I had less days of travel, than the record I, myself, had -- seems unbelievable, but this is true.