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	$42.84	6.846%	$45.7728	$45.77	$45.75	$45.80
Purchase #2	$159.95	8.829%	$174.072	$174.07	$174.05	$174.10
Purchase #3	$32.92	7.627%	$35.4308	$35.43	$35.45	$35.40
Purchase #4	$225.87	4.794%	$236.6982	$236.70	$236.70	$236.70
Purchase #5	$238.44	7.492%	$256.3039	$256.30	$256.30	$256.30
Purchase #6	$139.98	13.321%	$158.6267	$158.63	$158.65	$158.60
Purchase #7	$171.90	9.520%	$188.2649	$188.26	$188.25	$188.30
7 purchase totals =	$1,011.90		$1,095.1693	$1,095.16	$1,095.15	$1,095.20