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	$178.90	7.551%	$192.4087	$192.41	$192.40	$192.40
Purchase #2	$56.38	11.397%	$62.8056	$62.81	$62.80	$62.80
Purchase #3	$195.89	7.127%	$209.8511	$209.85	$209.85	$209.90
Purchase #4	$189.29	7.478%	$203.4451	$203.45	$203.45	$203.40
Purchase #5	$208.31	11.281%	$231.8095	$231.81	$231.80	$231.80
Purchase #6	$8.57	11.822%	$9.5831	$9.58	$9.60	$9.60
Purchase #7	$96.98	4.765%	$101.6011	$101.60	$101.60	$101.60
7 purchase totals =	$934.32		$1,011.5042	$1,011.51	$1,011.50	$1,011.50