Decision tree nodes overlapping with Tikz

I use yshift option to change the position of the nodes, to avoid overlapping.

I give two choice nodes some names (a and b) and draw a dashed line as usual.

Code:

\documentclass[tikz]{standalone}
\tikzset{
    choice/.style = {shape=rectangle, draw, align=center, color=black, fill=black, font=\normalsize},
    chance/.style = {shape=circle, draw, align=center, color=black, fill=black, font=\normalsize},
    root/.style = {choice, font=\normalsize, color=black},
    outcome/.style = {shape=rectangle, draw=white, align=center, font=\tiny, parent anchor=left},
}

\begin{document}
\begin{tikzpicture}
  [
    grow = right,
    sibling distance = 6em,
    level distance = 8em,
    edge from parent/.style = {draw, -latex},
    every node/.style = {font=\normalsize},
    sloped
  ]
\node [root] {}
    child {node [outcome, label=right:{\$30}] {}
        edge from parent node [below] {}}
    child {node [choice] {}
        child {node [chance] {}
        child {node [choice] (a) {}
            child {node [outcome, label=right:{\$10}]{}}
            child {node[yshift=-2em,outcome, label=right:{\$100}]{}}
            edge from parent node [below] {.5}}
        child {node [choice] (b) {}
            child {node [yshift=2em,outcome, label=right:{\$45}]{}}
            child {node [outcome, label=right:{\$55}]{}}
            edge from parent node [above] {.5}}
        edge from parent node [below] {}}
        child {node [outcome, label=right:{\$25}]{}
            edge from parent node [above] {}}
                    edge from parent node [above] {}};
\draw[dashed] (a)--(b);
\end{tikzpicture}
\end{document}

I would like to recommend forest, where the syntax is simpler and you do not have to worry about these things.

\documentclass{article}
\usepackage[edges]{forest}
\tikzset{
    choice/.style = {shape=rectangle, draw, align=center, color=black, fill=black},
    chance/.style = {shape=circle, draw, align=center, color=black, fill=black},
    root/.style = {choice, font=\normalsize, color=black},
    outcome/.style = {shape=rectangle, draw=white, align=center, font=\tiny, parent anchor=left},
}

\begin{document}
\begin{forest}
for tree={grow'=east,edge={-latex},l+=1cm}
[,root
 [,choice
  [\$25]
  [,chance
   [,choice,edge label={node[midway,above,sloped]{.5}}
    [\$55]
    [\$45]
   ]
   [,choice,edge label={node[midway,below,sloped]{.5}}
    [\$100]
    [\$10]
   ]
  ]
 ]
 [\$30]
]
\end{forest}
\end{document}