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	$114.39	9.579%	$125.3474	$125.35	$125.35	$125.30
Purchase #2	$92.90	4.249%	$96.8473	$96.85	$96.85	$96.80
Purchase #3	$164.38	13.264%	$186.1834	$186.18	$186.20	$186.20
Purchase #4	$78.90	7.869%	$85.1086	$85.11	$85.10	$85.10
Purchase #5	$145.35	11.326%	$161.8123	$161.81	$161.80	$161.80
Purchase #6	$176.70	11.259%	$196.5947	$196.59	$196.60	$196.60
Purchase #7	$217.85	7.460%	$234.1016	$234.10	$234.10	$234.10
7 purchase totals =	$990.47		$1,085.9953	$1,085.99	$1,086.00	$1,085.90