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	$161.88	3.397%	$167.3791	$167.38	$167.40	$167.40
Purchase #2	$12.44	12.170%	$13.9539	$13.95	$13.95	$14.00
Purchase #3	$179.29	7.337%	$192.4445	$192.44	$192.45	$192.40
Purchase #4	$178.91	9.836%	$196.5076	$196.51	$196.50	$196.50
Purchase #5	$138.38	3.426%	$143.1209	$143.12	$143.10	$143.10
Purchase #6	$182.88	9.357%	$199.9921	$199.99	$200.00	$200.00
Purchase #7	$59.59	4.707%	$62.3949	$62.39	$62.40	$62.40
7 purchase totals =	$913.37		$975.7930	$975.78	$975.80	$975.80