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	$62.69	4.869%	$65.7424	$65.74	$65.75	$65.70
Purchase #2	$154.74	3.236%	$159.7474	$159.75	$159.75	$159.70
Purchase #3	$87.83	12.315%	$98.6463	$98.65	$98.65	$98.60
Purchase #4	$147.89	13.845%	$168.3654	$168.37	$168.35	$168.40
Purchase #5	$58.45	5.402%	$61.6075	$61.61	$61.60	$61.60
Purchase #6	$42.61	13.816%	$48.497	$48.50	$48.50	$48.50
Purchase #7	$145.29	8.260%	$157.291	$157.29	$157.30	$157.30
7 purchase totals =	$699.50		$759.8970	$759.91	$759.90	$759.80