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	$121.73	7.312%	$130.6309	$130.63	$130.65	$130.60
Purchase #2	$74.88	7.691%	$80.639	$80.64	$80.65	$80.60
Purchase #3	$187.27	4.832%	$196.3189	$196.32	$196.30	$196.30
Purchase #4	$203.46	9.770%	$223.338	$223.34	$223.35	$223.30
Purchase #5	$47.59	6.597%	$50.7295	$50.73	$50.75	$50.70
Purchase #6	$99.50	12.153%	$111.5922	$111.59	$111.60	$111.60
Purchase #7	$200.41	6.448%	$213.3324	$213.33	$213.35	$213.30
7 purchase totals =	$934.84		$1,006.5809	$1,006.58	$1,006.65	$1,006.40