Before stopping, identify whether the word ends in «ة» or «ت». The rounded ta ending is sounded as ha in the ordinary pause, whereas open ta remains a t-sound, now still. Treating both identically loses a significant rule and can change the word's pronunciation.
In «رَحْمَةٌ», the rounded ta is heard like still ha when stopped upon.
In «بَيْتٌ», the written open ta remains t at the stop; the tanwin sound does not remain.
The purpose is not only to memorize two examples. The reciter should recognize the written ending, distinguish connected pronunciation from stopped pronunciation, and apply the right transformation. Not every word-final ta becomes ha in stopping.