Rounding improvement for budget model with `iterations > 1` #4199

Job	Run time
check-git-rev-deps	15s
cargo-deny (advisories)	46s
build-and-test (msrv, 22, ubuntu-latest, wasm32-unknown-unknown, false)	5m 40s
cackle	1m 22s
build-and-test (msrv, 22, ubuntu-latest-16-cores, x86_64-unknown-linux-gnu, true)	12m 11s
cargo-deny (bans licenses sources)	49s
build-and-test (latest, 22, ubuntu-latest, wasm32-unknown-unknown, false)	5m 23s
fmt	14s
publish-dry-run	0s
build-and-test (latest, 22, ubuntu-latest-16-cores, x86_64-unknown-linux-gnu, true)	10m 54s
semver-checks	4m 20s
complete	1s
	41m 55s

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