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	$168.65	13.451%	$191.3351	$191.34	$191.35	$191.30
Purchase #2	$146.65	3.215%	$151.3648	$151.36	$151.35	$151.40
Purchase #3	$250.30	4.226%	$260.8777	$260.88	$260.90	$260.90
Purchase #4	$166.61	10.476%	$184.0641	$184.06	$184.05	$184.10
Purchase #5	$61.78	3.139%	$63.7193	$63.72	$63.70	$63.70
Purchase #6	$60.70	11.656%	$67.7752	$67.78	$67.80	$67.80
Purchase #7	$191.55	8.747%	$208.3049	$208.30	$208.30	$208.30
7 purchase totals =	$1,046.24		$1,127.4411	$1,127.44	$1,127.45	$1,127.50