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	$215.50	5.793%	$227.9839	$227.98	$228.00	$228.00
Purchase #2	$54.60	4.566%	$57.093	$57.09	$57.10	$57.10
Purchase #3	$168.60	8.254%	$182.5162	$182.52	$182.50	$182.50
Purchase #4	$167.61	8.403%	$181.6943	$181.69	$181.70	$181.70
Purchase #5	$14.67	3.277%	$15.1507	$15.15	$15.15	$15.20
Purchase #6	$173.98	6.340%	$185.0103	$185.01	$185.00	$185.00
Purchase #7	$162.43	6.464%	$172.9295	$172.93	$172.95	$172.90
7 purchase totals =	$957.39		$1,022.3779	$1,022.37	$1,022.40	$1,022.40