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	$196.37	11.288%	$218.5362	$218.54	$218.55	$218.50
Purchase #2	$48.32	7.520%	$51.9537	$51.95	$51.95	$52.00
Purchase #3	$232.70	12.228%	$261.1546	$261.15	$261.15	$261.20
Purchase #4	$104.48	4.267%	$108.9382	$108.94	$108.95	$108.90
Purchase #5	$62.44	8.569%	$67.7905	$67.79	$67.80	$67.80
Purchase #6	$226.39	10.845%	$250.942	$250.94	$250.95	$250.90
Purchase #7	$54.65	10.576%	$60.4298	$60.43	$60.45	$60.40
7 purchase totals =	$925.35		$1,019.7450	$1,019.74	$1,019.80	$1,019.70