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	$143.79	11.714%	$160.6336	$160.63	$160.65	$160.60
Purchase #2	$11.90	12.823%	$13.4259	$13.43	$13.45	$13.40
Purchase #3	$243.89	11.269%	$271.374	$271.37	$271.35	$271.40
Purchase #4	$55.37	7.285%	$59.4037	$59.40	$59.40	$59.40
Purchase #5	$230.50	3.365%	$238.2563	$238.26	$238.25	$238.30
Purchase #6	$134.34	12.142%	$150.6516	$150.65	$150.65	$150.70
Purchase #7	$115.77	6.477%	$123.2684	$123.27	$123.25	$123.30
7 purchase totals =	$935.56		$1,017.0135	$1,017.01	$1,017.00	$1,017.10