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	$191.59	7.467%	$205.896	$205.90	$205.90	$205.90
Purchase #2	$80.79	5.855%	$85.5203	$85.52	$85.50	$85.50
Purchase #3	$81.55	4.591%	$85.294	$85.29	$85.30	$85.30
Purchase #4	$115.96	7.594%	$124.766	$124.77	$124.75	$124.80
Purchase #5	$147.55	3.379%	$152.5357	$152.54	$152.55	$152.50
Purchase #6	$177.73	5.407%	$187.3399	$187.34	$187.35	$187.30
Purchase #7	$161.28	9.522%	$176.6371	$176.64	$176.65	$176.60
7 purchase totals =	$956.45		$1,017.9890	$1,018.00	$1,018.00	$1,017.90