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	$218.49	8.419%	$236.8847	$236.88	$236.90	$236.90
Purchase #2	$91.88	9.519%	$100.6261	$100.63	$100.65	$100.60
Purchase #3	$182.80	3.306%	$188.8434	$188.84	$188.85	$188.80
Purchase #4	$221.80	10.832%	$245.8254	$245.83	$245.85	$245.80
Purchase #5	$180.32	4.473%	$188.3857	$188.39	$188.40	$188.40
Purchase #6	$33.78	9.542%	$37.0033	$37.00	$37.00	$37.00
Purchase #7	$157.81	8.627%	$171.4243	$171.42	$171.40	$171.40
7 purchase totals =	$1,086.88		$1,168.9929	$1,168.99	$1,169.05	$1,168.90