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	$213.75	11.660%	$238.6733	$238.67	$238.65	$238.70
Purchase #2	$144.65	12.207%	$162.3074	$162.31	$162.30	$162.30
Purchase #3	$179.99	11.407%	$200.5215	$200.52	$200.50	$200.50
Purchase #4	$167.28	12.708%	$188.5379	$188.54	$188.55	$188.50
Purchase #5	$74.50	12.201%	$83.5897	$83.59	$83.60	$83.60
Purchase #6	$58.65	5.836%	$62.0728	$62.07	$62.05	$62.10
Purchase #7	$249.84	5.815%	$264.3682	$264.37	$264.35	$264.40
7 purchase totals =	$1,088.66		$1,200.0708	$1,200.07	$1,200.00	$1,200.10