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	$60.42	4.718%	$63.2706	$63.27	$63.25	$63.30
Purchase #2	$170.66	6.617%	$181.9526	$181.95	$181.95	$182.00
Purchase #3	$76.37	7.328%	$81.9664	$81.97	$81.95	$82.00
Purchase #4	$235.91	6.232%	$250.6119	$250.61	$250.60	$250.60
Purchase #5	$172.58	7.446%	$185.4303	$185.43	$185.45	$185.40
Purchase #6	$94.39	10.823%	$104.6058	$104.61	$104.60	$104.60
Purchase #7	$212.51	5.326%	$223.8283	$223.83	$223.85	$223.80
7 purchase totals =	$1,022.84		$1,091.6659	$1,091.67	$1,091.65	$1,091.70