I achieve good "slow-down" endings (I like that name better than "ritardando") with Band-in-a-Box (BiaB).

I've found the top, numeric entry works well when abrupt tempo changes are desired, such as a tempo change between verse and chorus.

The bottom, percentage entry works well at the end of the song. I stretch the tempo change over three to six bars with each bar having a progressively higher percentage.

Slowing down over multiple bars and then using a hold ( chord with three dots like C ...) in the last bar works great in a ballad.

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F5 Tempo Change Options

Jim Fogle - 2025 BiaB (Build 1128) RB (Build 5) - Ultra+ PAK
DAWs: Cakewalk Sonar - Standalone: Zoom MRS-8
Laptop: i3 Win 10, 8GB ram 500GB HDD
Desktop: i7 Win 11, 12GB ram 256GB SSD, 4 TB HDD
Music at: https://fogle622.wix.com/fogle622-audio-home