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	$50.59	8.710%	$54.9964	$55.00	$55.00	$55.00
Purchase #2	$128.34	13.136%	$145.1987	$145.20	$145.20	$145.20
Purchase #3	$171.64	10.580%	$189.7995	$189.80	$189.80	$189.80
Purchase #4	$175.29	3.567%	$181.5426	$181.54	$181.55	$181.50
Purchase #5	$104.81	6.298%	$111.4109	$111.41	$111.40	$111.40
Purchase #6	$155.82	5.383%	$164.2078	$164.21	$164.20	$164.20
Purchase #7	$156.88	6.815%	$167.5714	$167.57	$167.55	$167.60
7 purchase totals =	$943.37		$1,014.7273	$1,014.73	$1,014.70	$1,014.70