Expand use of Asset::integral()

include/xrpl/protocol/STAmount.h

@@ -174,6 +174,9 @@ public:
     int
     exponent() const noexcept;
 
+    bool
+    integral() const noexcept;
+
     bool
     native() const noexcept;
 
@@ -454,6 +457,12 @@ STAmount::exponent() const noexcept
     return mOffset;
 }
 
+inline bool
+STAmount::integral() const noexcept
+{
+    return mAsset.integral();
+}
+
 inline bool
 STAmount::native() const noexcept
 {
@@ -735,7 +744,7 @@ roundToAsset(
 {
     NumberRoundModeGuard mg(rounding);
     STAmount const ret{asset, value};
-    if (ret.asset().native() || !ret.asset().holds<Issue>())
+    if (ret.integral())
         return ret;
     // Not that the ctor will round integral types (XRP, MPT) via canonicalize,
     // so no extra work is needed for those.