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	$148.49	7.714%	$159.9445	$159.94	$159.95	$159.90
Purchase #2	$225.27	13.322%	$255.2805	$255.28	$255.30	$255.30
Purchase #3	$153.62	5.109%	$161.4684	$161.47	$161.45	$161.50
Purchase #4	$192.79	13.398%	$218.62	$218.62	$218.60	$218.60
Purchase #5	$204.44	8.500%	$221.8174	$221.82	$221.80	$221.80
Purchase #6	$38.60	13.379%	$43.7643	$43.76	$43.75	$43.80
Purchase #7	$227.30	11.472%	$253.3759	$253.38	$253.40	$253.40
7 purchase totals =	$1,190.51		$1,314.2710	$1,314.27	$1,314.25	$1,314.30