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	$208.86	10.635%	$231.0723	$231.07	$231.05	$231.10
Purchase #2	$71.90	6.487%	$76.5642	$76.56	$76.55	$76.60
Purchase #3	$159.66	5.480%	$168.4094	$168.41	$168.40	$168.40
Purchase #4	$210.52	5.592%	$222.2923	$222.29	$222.30	$222.30
Purchase #5	$113.32	5.676%	$119.752	$119.75	$119.75	$119.80
Purchase #6	$100.52	3.455%	$103.993	$103.99	$104.00	$104.00
Purchase #7	$116.78	4.764%	$122.3434	$122.34	$122.35	$122.30
7 purchase totals =	$981.56		$1,044.4266	$1,044.41	$1,044.40	$1,044.50