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	$241.81	11.274%	$269.0717	$269.07	$269.05	$269.10
Purchase #2	$84.31	8.625%	$91.5817	$91.58	$91.60	$91.60
Purchase #3	$91.55	4.194%	$95.3896	$95.39	$95.40	$95.40
Purchase #4	$184.81	4.216%	$192.6016	$192.60	$192.60	$192.60
Purchase #5	$207.32	11.596%	$231.3608	$231.36	$231.35	$231.40
Purchase #6	$169.57	5.237%	$178.4504	$178.45	$178.45	$178.50
Purchase #7	$103.96	5.402%	$109.5759	$109.58	$109.60	$109.60
7 purchase totals =	$1,083.33		$1,168.0317	$1,168.03	$1,168.05	$1,168.20