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	$211.45	8.477%	$229.3746	$229.37	$229.35	$229.40
Purchase #2	$38.55	12.267%	$43.2789	$43.28	$43.30	$43.30
Purchase #3	$108.34	13.544%	$123.0136	$123.01	$123.00	$123.00
Purchase #4	$83.43	7.368%	$89.5771	$89.58	$89.60	$89.60
Purchase #5	$83.89	12.843%	$94.664	$94.66	$94.65	$94.70
Purchase #6	$230.88	9.105%	$251.9016	$251.90	$251.90	$251.90
Purchase #7	$198.91	6.585%	$212.0082	$212.01	$212.00	$212.00
7 purchase totals =	$955.45		$1,043.8180	$1,043.81	$1,043.80	$1,043.90