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	$177.26	10.845%	$196.4838	$196.48	$196.50	$196.50
Purchase #2	$6.66	6.681%	$7.105	$7.11	$7.10	$7.10
Purchase #3	$201.53	7.438%	$216.5198	$216.52	$216.50	$216.50
Purchase #4	$157.63	9.515%	$172.6285	$172.63	$172.65	$172.60
Purchase #5	$162.46	3.618%	$168.3378	$168.34	$168.35	$168.30
Purchase #6	$193.47	13.777%	$220.1244	$220.12	$220.10	$220.10
Purchase #7	$74.70	12.397%	$83.9606	$83.96	$83.95	$84.00
7 purchase totals =	$973.71		$1,065.1599	$1,065.16	$1,065.15	$1,065.10