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	$94.64	10.164%	$104.2592	$104.26	$104.25	$104.30
Purchase #2	$205.48	13.562%	$233.3472	$233.35	$233.35	$233.30
Purchase #3	$75.26	4.107%	$78.3509	$78.35	$78.35	$78.40
Purchase #4	$138.78	6.870%	$148.3142	$148.31	$148.30	$148.30
Purchase #5	$153.55	12.252%	$172.3629	$172.36	$172.35	$172.40
Purchase #6	$219.53	7.816%	$236.6885	$236.69	$236.70	$236.70
Purchase #7	$93.94	10.867%	$104.1485	$104.15	$104.15	$104.10
7 purchase totals =	$981.18		$1,077.4714	$1,077.47	$1,077.45	$1,077.50