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	$44.37	3.280%	$45.8253	$45.83	$45.85	$45.80
Purchase #2	$85.61	5.627%	$90.4273	$90.43	$90.45	$90.40
Purchase #3	$114.39	6.154%	$121.4296	$121.43	$121.45	$121.40
Purchase #4	$182.90	5.739%	$193.3966	$193.40	$193.40	$193.40
Purchase #5	$156.96	11.861%	$175.577	$175.58	$175.60	$175.60
Purchase #6	$178.93	5.368%	$188.535	$188.54	$188.55	$188.50
Purchase #7	$176.82	12.852%	$199.5449	$199.54	$199.55	$199.50
7 purchase totals =	$939.98		$1,014.7357	$1,014.75	$1,014.85	$1,014.60