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	$165.98	6.286%	$176.4135	$176.41	$176.40	$176.40
Purchase #2	$113.48	9.147%	$123.86	$123.86	$123.85	$123.90
Purchase #3	$147.33	7.627%	$158.5669	$158.57	$158.55	$158.60
Purchase #4	$137.45	6.622%	$146.5519	$146.55	$146.55	$146.60
Purchase #5	$44.60	6.695%	$47.586	$47.59	$47.60	$47.60
Purchase #6	$244.39	5.202%	$257.1032	$257.10	$257.10	$257.10
Purchase #7	$177.46	4.666%	$185.7403	$185.74	$185.75	$185.70
7 purchase totals =	$1,030.69		$1,095.8218	$1,095.82	$1,095.80	$1,095.90