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	$176.73	11.380%	$196.8419	$196.84	$196.85	$196.80
Purchase #2	$13.33	12.417%	$14.9852	$14.99	$15.00	$15.00
Purchase #3	$62.67	7.147%	$67.149	$67.15	$67.15	$67.10
Purchase #4	$184.80	11.577%	$206.1943	$206.19	$206.20	$206.20
Purchase #5	$189.90	8.150%	$205.3769	$205.38	$205.40	$205.40
Purchase #6	$124.55	5.536%	$131.4451	$131.45	$131.45	$131.40
Purchase #7	$161.36	11.449%	$179.8341	$179.83	$179.85	$179.80
7 purchase totals =	$913.34		$1,001.8265	$1,001.83	$1,001.90	$1,001.70