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	$94.54	4.524%	$98.817	$98.82	$98.80	$98.80
Purchase #2	$42.61	8.552%	$46.254	$46.25	$46.25	$46.30
Purchase #3	$180.67	10.269%	$199.223	$199.22	$199.20	$199.20
Purchase #4	$168.60	4.840%	$176.7602	$176.76	$176.75	$176.80
Purchase #5	$164.70	9.774%	$180.7978	$180.80	$180.80	$180.80
Purchase #6	$157.34	13.383%	$178.3968	$178.40	$178.40	$178.40
Purchase #7	$143.36	10.835%	$158.8931	$158.89	$158.90	$158.90
7 purchase totals =	$951.82		$1,039.1419	$1,039.14	$1,039.10	$1,039.20