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	$44.31	7.487%	$47.6275	$47.63	$47.65	$47.60
Purchase #2	$150.51	12.444%	$169.2395	$169.24	$169.25	$169.20
Purchase #3	$150.86	7.725%	$162.5139	$162.51	$162.50	$162.50
Purchase #4	$199.98	13.781%	$227.5392	$227.54	$227.55	$227.50
Purchase #5	$61.81	9.843%	$67.894	$67.89	$67.90	$67.90
Purchase #6	$182.78	5.312%	$192.4893	$192.49	$192.50	$192.50
Purchase #7	$212.85	7.372%	$228.5413	$228.54	$228.55	$228.50
7 purchase totals =	$1,003.10		$1,095.8447	$1,095.84	$1,095.90	$1,095.70