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	$59.61	4.648%	$62.3807	$62.38	$62.40	$62.40
Purchase #2	$52.25	13.681%	$59.3983	$59.40	$59.40	$59.40
Purchase #3	$36.95	6.374%	$39.3052	$39.31	$39.30	$39.30
Purchase #4	$243.73	4.634%	$255.0244	$255.02	$255.00	$255.00
Purchase #5	$86.90	9.371%	$95.0434	$95.04	$95.05	$95.00
Purchase #6	$180.78	10.480%	$199.7257	$199.73	$199.75	$199.70
Purchase #7	$36.67	6.504%	$39.055	$39.06	$39.05	$39.10
7 purchase totals =	$696.89		$749.9327	$749.94	$749.95	$749.90