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	$193.81	3.409%	$200.417	$200.42	$200.40	$200.40
Purchase #2	$20.61	3.534%	$21.3384	$21.34	$21.35	$21.30
Purchase #3	$142.86	13.819%	$162.6018	$162.60	$162.60	$162.60
Purchase #4	$98.38	5.567%	$103.8568	$103.86	$103.85	$103.90
Purchase #5	$15.42	13.613%	$17.5191	$17.52	$17.50	$17.50
Purchase #6	$187.46	4.184%	$195.3033	$195.30	$195.30	$195.30
Purchase #7	$39.41	6.466%	$41.9583	$41.96	$41.95	$42.00
7 purchase totals =	$697.95		$742.9947	$743.00	$742.95	$743.00