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	$70.95	10.565%	$78.4459	$78.45	$78.45	$78.40
Purchase #2	$92.39	11.479%	$102.9954	$103.00	$103.00	$103.00
Purchase #3	$83.60	9.372%	$91.435	$91.44	$91.45	$91.40
Purchase #4	$105.43	8.401%	$114.2872	$114.29	$114.30	$114.30
Purchase #5	$152.91	12.660%	$172.2684	$172.27	$172.25	$172.30
Purchase #6	$186.43	6.572%	$198.6822	$198.68	$198.70	$198.70
Purchase #7	$220.78	11.632%	$246.4611	$246.46	$246.45	$246.50
7 purchase totals =	$912.49		$1,004.5752	$1,004.59	$1,004.60	$1,004.60