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	$86.32	10.164%	$95.0936	$95.09	$95.10	$95.10
Purchase #2	$71.93	9.366%	$78.667	$78.67	$78.65	$78.70
Purchase #3	$70.96	10.130%	$78.1482	$78.15	$78.15	$78.10
Purchase #4	$168.65	12.269%	$189.3417	$189.34	$189.35	$189.30
Purchase #5	$73.83	3.250%	$76.2295	$76.23	$76.25	$76.20
Purchase #6	$166.38	12.520%	$187.2108	$187.21	$187.20	$187.20
Purchase #7	$89.57	13.671%	$101.8151	$101.82	$101.80	$101.80
7 purchase totals =	$727.64		$806.5059	$806.51	$806.50	$806.40