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	$39.40	11.552%	$43.9515	$43.95	$43.95	$44.00
Purchase #2	$19.25	3.387%	$19.902	$19.90	$19.90	$19.90
Purchase #3	$174.75	12.412%	$196.44	$196.44	$196.45	$196.40
Purchase #4	$76.61	11.419%	$85.3581	$85.36	$85.35	$85.40
Purchase #5	$230.70	12.293%	$259.06	$259.06	$259.05	$259.10
Purchase #6	$107.55	3.852%	$111.6928	$111.69	$111.70	$111.70
Purchase #7	$175.50	3.835%	$182.2304	$182.23	$182.25	$182.20
7 purchase totals =	$823.76		$898.6348	$898.63	$898.65	$898.70