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	$71.89	6.370%	$76.4694	$76.47	$76.45	$76.50
Purchase #2	$73.90	11.320%	$82.2655	$82.27	$82.25	$82.30
Purchase #3	$119.83	13.551%	$136.0682	$136.07	$136.05	$136.10
Purchase #4	$39.61	8.716%	$43.0624	$43.06	$43.05	$43.10
Purchase #5	$220.70	12.697%	$248.7223	$248.72	$248.70	$248.70
Purchase #6	$177.40	3.673%	$183.9159	$183.92	$183.90	$183.90
Purchase #7	$220.46	10.609%	$243.8486	$243.85	$243.85	$243.80
7 purchase totals =	$923.79		$1,014.3523	$1,014.36	$1,014.25	$1,014.40