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	$184.76	7.636%	$198.8683	$198.87	$198.85	$198.90
Purchase #2	$159.30	7.534%	$171.3017	$171.30	$171.30	$171.30
Purchase #3	$176.63	12.583%	$198.8554	$198.86	$198.85	$198.90
Purchase #4	$107.59	7.823%	$116.0068	$116.01	$116.00	$116.00
Purchase #5	$221.68	5.479%	$233.8258	$233.83	$233.85	$233.80
Purchase #6	$216.51	6.364%	$230.2887	$230.29	$230.30	$230.30
Purchase #7	$89.43	7.709%	$96.3242	$96.32	$96.30	$96.30
7 purchase totals =	$1,155.90		$1,245.4709	$1,245.48	$1,245.45	$1,245.50