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	$95.40	5.523%	$100.6689	$100.67	$100.65	$100.70
Purchase #2	$12.47	8.562%	$13.5377	$13.54	$13.55	$13.50
Purchase #3	$163.74	5.535%	$172.803	$172.80	$172.80	$172.80
Purchase #4	$169.62	7.167%	$181.7767	$181.78	$181.80	$181.80
Purchase #5	$228.81	3.826%	$237.5643	$237.56	$237.55	$237.60
Purchase #6	$236.93	5.688%	$250.4066	$250.41	$250.40	$250.40
Purchase #7	$240.41	10.464%	$265.5665	$265.57	$265.55	$265.60
7 purchase totals =	$1,147.38		$1,222.3237	$1,222.33	$1,222.30	$1,222.40