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	$62.57	7.550%	$67.294	$67.29	$67.30	$67.30
Purchase #2	$196.88	9.249%	$215.0894	$215.09	$215.10	$215.10
Purchase #3	$136.70	10.383%	$150.8936	$150.89	$150.90	$150.90
Purchase #4	$41.32	11.105%	$45.9086	$45.91	$45.90	$45.90
Purchase #5	$137.77	8.708%	$149.767	$149.77	$149.75	$149.80
Purchase #6	$216.67	3.450%	$224.1451	$224.15	$224.15	$224.10
Purchase #7	$161.85	10.684%	$179.1421	$179.14	$179.15	$179.10
7 purchase totals =	$953.76		$1,032.2398	$1,032.24	$1,032.25	$1,032.20