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	$140.90	7.358%	$151.2674	$151.27	$151.25	$151.30
Purchase #2	$246.27	3.738%	$255.4756	$255.48	$255.50	$255.50
Purchase #3	$209.39	7.214%	$224.4954	$224.50	$224.50	$224.50
Purchase #4	$10.66	4.792%	$11.1708	$11.17	$11.15	$11.20
Purchase #5	$240.98	7.377%	$258.7571	$258.76	$258.75	$258.80
Purchase #6	$38.26	13.351%	$43.3681	$43.37	$43.35	$43.40
Purchase #7	$87.33	6.558%	$93.0571	$93.06	$93.05	$93.10
7 purchase totals =	$973.79		$1,037.5915	$1,037.61	$1,037.55	$1,037.80