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	$186.96	13.851%	$212.8558	$212.86	$212.85	$212.90
Purchase #2	$10.34	5.819%	$10.9417	$10.94	$10.95	$10.90
Purchase #3	$122.64	11.306%	$136.5057	$136.51	$136.50	$136.50
Purchase #4	$226.85	13.465%	$257.3954	$257.40	$257.40	$257.40
Purchase #5	$172.47	7.365%	$185.1724	$185.17	$185.15	$185.20
Purchase #6	$86.59	5.775%	$91.5906	$91.59	$91.60	$91.60
Purchase #7	$99.95	13.770%	$113.7131	$113.71	$113.70	$113.70
7 purchase totals =	$905.80		$1,008.1747	$1,008.18	$1,008.15	$1,008.20