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	$24.72	3.577%	$25.6042	$25.60	$25.60	$25.60
Purchase #2	$39.98	5.320%	$42.1069	$42.11	$42.10	$42.10
Purchase #3	$162.75	12.596%	$183.25	$183.25	$183.25	$183.30
Purchase #4	$238.31	3.289%	$246.148	$246.15	$246.15	$246.10
Purchase #5	$83.42	3.398%	$86.2546	$86.25	$86.25	$86.30
Purchase #6	$173.49	7.582%	$186.644	$186.64	$186.65	$186.60
Purchase #7	$250.39	11.268%	$278.6039	$278.60	$278.60	$278.60
7 purchase totals =	$973.06		$1,048.6116	$1,048.60	$1,048.60	$1,048.60