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	$136.61	3.819%	$141.8271	$141.83	$141.85	$141.80
Purchase #2	$218.84	5.190%	$230.1978	$230.20	$230.20	$230.20
Purchase #3	$204.91	3.402%	$211.881	$211.88	$211.90	$211.90
Purchase #4	$158.89	9.455%	$173.913	$173.91	$173.90	$173.90
Purchase #5	$138.90	8.606%	$150.8537	$150.85	$150.85	$150.90
Purchase #6	$40.84	5.851%	$43.2295	$43.23	$43.25	$43.20
Purchase #7	$220.42	10.785%	$244.1923	$244.19	$244.20	$244.20
7 purchase totals =	$1,119.41		$1,196.0944	$1,196.09	$1,196.15	$1,196.10