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	$191.63	7.238%	$205.5002	$205.50	$205.50	$205.50
Purchase #2	$233.31	13.382%	$264.5315	$264.53	$264.55	$264.50
Purchase #3	$247.48	11.832%	$276.7618	$276.76	$276.75	$276.80
Purchase #4	$240.72	7.424%	$258.5911	$258.59	$258.60	$258.60
Purchase #5	$40.73	12.738%	$45.9182	$45.92	$45.90	$45.90
Purchase #6	$100.44	4.213%	$104.6715	$104.67	$104.65	$104.70
Purchase #7	$19.41	6.223%	$20.6179	$20.62	$20.60	$20.60
7 purchase totals =	$1,073.72		$1,176.5922	$1,176.59	$1,176.55	$1,176.60