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	$191.29	9.195%	$208.8791	$208.88	$208.90	$208.90
Purchase #2	$161.29	9.497%	$176.6077	$176.61	$176.60	$176.60
Purchase #3	$94.76	7.500%	$101.867	$101.87	$101.85	$101.90
Purchase #4	$184.69	6.388%	$196.488	$196.49	$196.50	$196.50
Purchase #5	$162.88	8.538%	$176.7867	$176.79	$176.80	$176.80
Purchase #6	$94.60	3.489%	$97.9006	$97.90	$97.90	$97.90
Purchase #7	$138.30	9.457%	$151.379	$151.38	$151.40	$151.40
7 purchase totals =	$1,027.81		$1,109.9081	$1,109.92	$1,109.95	$1,110.00