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	$164.95	10.260%	$181.8739	$181.87	$181.85	$181.90
Purchase #2	$6.39	13.248%	$7.2365	$7.24	$7.25	$7.20
Purchase #3	$110.44	12.133%	$123.8397	$123.84	$123.85	$123.80
Purchase #4	$240.70	7.184%	$257.9919	$257.99	$258.00	$258.00
Purchase #5	$212.71	4.656%	$222.6138	$222.61	$222.60	$222.60
Purchase #6	$198.91	12.253%	$223.2824	$223.28	$223.30	$223.30
Purchase #7	$164.59	8.690%	$178.8929	$178.89	$178.90	$178.90
7 purchase totals =	$1,098.69		$1,195.7311	$1,195.72	$1,195.75	$1,195.70