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	$158.25	8.334%	$171.4386	$171.44	$171.45	$171.40
Purchase #2	$225.42	8.646%	$244.9098	$244.91	$244.90	$244.90
Purchase #3	$33.64	4.714%	$35.2258	$35.23	$35.25	$35.20
Purchase #4	$46.55	11.360%	$51.8381	$51.84	$51.85	$51.80
Purchase #5	$247.45	12.556%	$278.5198	$278.52	$278.50	$278.50
Purchase #6	$102.42	8.770%	$111.4022	$111.40	$111.40	$111.40
Purchase #7	$208.60	3.290%	$215.4629	$215.46	$215.45	$215.50
7 purchase totals =	$1,022.33		$1,108.7972	$1,108.80	$1,108.80	$1,108.70