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	$176.67	11.351%	$196.7238	$196.72	$196.70	$196.70
Purchase #2	$77.34	6.633%	$82.47	$82.47	$82.45	$82.50
Purchase #3	$80.86	3.783%	$83.9189	$83.92	$83.90	$83.90
Purchase #4	$230.39	7.495%	$247.6577	$247.66	$247.65	$247.70
Purchase #5	$28.79	3.463%	$29.787	$29.79	$29.80	$29.80
Purchase #6	$250.31	12.451%	$281.4761	$281.48	$281.50	$281.50
Purchase #7	$184.92	6.335%	$196.6347	$196.63	$196.65	$196.60
7 purchase totals =	$1,029.28		$1,118.6682	$1,118.67	$1,118.65	$1,118.70