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	$184.68	11.258%	$205.4713	$205.47	$205.45	$205.50
Purchase #2	$184.35	6.688%	$196.6793	$196.68	$196.70	$196.70
Purchase #3	$33.39	4.453%	$34.8769	$34.88	$34.90	$34.90
Purchase #4	$38.61	11.506%	$43.0525	$43.05	$43.05	$43.10
Purchase #5	$155.40	10.339%	$171.4668	$171.47	$171.45	$171.50
Purchase #6	$41.45	10.407%	$45.7637	$45.76	$45.75	$45.80
Purchase #7	$101.54	11.778%	$113.4994	$113.50	$113.50	$113.50
7 purchase totals =	$739.42		$810.8099	$810.81	$810.80	$811.00