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	$57.30	3.791%	$59.4722	$59.47	$59.45	$59.50
Purchase #2	$25.70	7.309%	$27.5784	$27.58	$27.60	$27.60
Purchase #3	$90.59	7.863%	$97.7131	$97.71	$97.70	$97.70
Purchase #4	$162.79	7.351%	$174.7567	$174.76	$174.75	$174.80
Purchase #5	$178.62	6.570%	$190.3553	$190.36	$190.35	$190.40
Purchase #6	$184.74	11.161%	$205.3588	$205.36	$205.35	$205.40
Purchase #7	$246.89	4.237%	$257.3507	$257.35	$257.35	$257.40
7 purchase totals =	$946.63		$1,012.5852	$1,012.59	$1,012.55	$1,012.80