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	$112.26	11.275%	$124.9173	$124.92	$124.90	$124.90
Purchase #2	$197.72	3.717%	$205.0693	$205.07	$205.05	$205.10
Purchase #3	$204.55	5.503%	$215.8064	$215.81	$215.80	$215.80
Purchase #4	$106.37	12.424%	$119.5854	$119.59	$119.60	$119.60
Purchase #5	$164.86	13.113%	$186.4781	$186.48	$186.50	$186.50
Purchase #6	$170.30	10.386%	$187.9874	$187.99	$188.00	$188.00
Purchase #7	$19.47	11.267%	$21.6637	$21.66	$21.65	$21.70
7 purchase totals =	$975.53		$1,061.5076	$1,061.52	$1,061.50	$1,061.60