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	$70.44	3.265%	$72.7399	$72.74	$72.75	$72.70
Purchase #2	$186.37	5.396%	$196.4265	$196.43	$196.45	$196.40
Purchase #3	$40.85	9.765%	$44.839	$44.84	$44.85	$44.80
Purchase #4	$95.55	6.493%	$101.7541	$101.75	$101.75	$101.80
Purchase #5	$208.90	4.592%	$218.4927	$218.49	$218.50	$218.50
Purchase #6	$198.64	5.461%	$209.4877	$209.49	$209.50	$209.50
Purchase #7	$222.25	4.677%	$232.6446	$232.64	$232.65	$232.60
7 purchase totals =	$1,023.00		$1,076.3845	$1,076.38	$1,076.45	$1,076.30