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	$226.49	10.703%	$250.7312	$250.73	$250.75	$250.70
Purchase #2	$58.56	11.761%	$65.4472	$65.45	$65.45	$65.40
Purchase #3	$232.87	3.596%	$241.244	$241.24	$241.25	$241.20
Purchase #4	$40.46	9.531%	$44.3162	$44.32	$44.30	$44.30
Purchase #5	$40.57	5.703%	$42.8837	$42.88	$42.90	$42.90
Purchase #6	$234.79	10.510%	$259.4664	$259.47	$259.45	$259.50
Purchase #7	$187.45	11.190%	$208.4257	$208.43	$208.45	$208.40
7 purchase totals =	$1,021.19		$1,112.5144	$1,112.52	$1,112.55	$1,112.40