Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$184.27	13.669%	$209.4579	$209.46	$209.45	$209.50
Purchase #2	$29.73	13.750%	$33.8179	$33.82	$33.80	$33.80
Purchase #3	$77.73	3.337%	$80.3239	$80.32	$80.30	$80.30
Purchase #4	$194.81	10.260%	$214.7975	$214.80	$214.80	$214.80
Purchase #5	$244.83	13.610%	$278.1514	$278.15	$278.15	$278.20
Purchase #6	$175.52	7.321%	$188.3698	$188.37	$188.35	$188.40
Purchase #7	$93.43	3.258%	$96.4739	$96.47	$96.45	$96.50
7 purchase totals =	$1,000.32		$1,101.3923	$1,101.39	$1,101.30	$1,101.50