Is there a way for me to force trendlines to snap to the high and/or low price of a bar?

Yes, simply setup the Trendline with "Snap to Price: Nearest High or Low" as seen in the trendline preference window below. This option is the first option in the drop down list box. When trendlines are setup in this fashion, they will snap to the nearest high or low of the bar to which they are dropped or dragged.

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