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	$177.65	8.559%	$192.8551	$192.86	$192.85	$192.90
Purchase #2	$176.53	10.376%	$194.8468	$194.85	$194.85	$194.80
Purchase #3	$91.54	7.121%	$98.0586	$98.06	$98.05	$98.10
Purchase #4	$110.67	11.799%	$123.728	$123.73	$123.75	$123.70
Purchase #5	$197.31	12.739%	$222.4453	$222.45	$222.45	$222.40
Purchase #6	$47.69	12.824%	$53.8058	$53.81	$53.80	$53.80
Purchase #7	$178.37	5.256%	$187.7451	$187.75	$187.75	$187.70
7 purchase totals =	$979.76		$1,073.4847	$1,073.51	$1,073.50	$1,073.40