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	$102.83	3.482%	$106.4105	$106.41	$106.40	$106.40
Purchase #2	$13.91	10.685%	$15.3963	$15.40	$15.40	$15.40
Purchase #3	$35.78	4.442%	$37.3693	$37.37	$37.35	$37.40
Purchase #4	$94.66	6.565%	$100.8744	$100.87	$100.85	$100.90
Purchase #5	$233.79	9.618%	$256.2759	$256.28	$256.30	$256.30
Purchase #6	$131.63	4.394%	$137.4138	$137.41	$137.40	$137.40
Purchase #7	$190.81	12.598%	$214.8482	$214.85	$214.85	$214.80
7 purchase totals =	$803.41		$868.5884	$868.59	$868.55	$868.60