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	$177.50	10.651%	$196.4055	$196.41	$196.40	$196.40
Purchase #2	$21.89	9.141%	$23.891	$23.89	$23.90	$23.90
Purchase #3	$73.45	3.619%	$76.1082	$76.11	$76.10	$76.10
Purchase #4	$73.56	13.332%	$83.367	$83.37	$83.35	$83.40
Purchase #5	$87.38	12.323%	$98.1478	$98.15	$98.15	$98.10
Purchase #6	$154.90	13.776%	$176.239	$176.24	$176.25	$176.20
Purchase #7	$86.86	12.184%	$97.443	$97.44	$97.45	$97.40
7 purchase totals =	$675.54		$751.6015	$751.61	$751.60	$751.50