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	$222.34	3.617%	$230.382	$230.38	$230.40	$230.40
Purchase #2	$5.83	12.853%	$6.5793	$6.58	$6.60	$6.60
Purchase #3	$243.90	7.288%	$261.6754	$261.68	$261.70	$261.70
Purchase #4	$95.37	10.450%	$105.3362	$105.34	$105.35	$105.30
Purchase #5	$127.31	3.222%	$131.4119	$131.41	$131.40	$131.40
Purchase #6	$175.33	3.478%	$181.428	$181.43	$181.45	$181.40
Purchase #7	$179.93	3.835%	$186.8303	$186.83	$186.85	$186.80
7 purchase totals =	$1,050.01		$1,103.6431	$1,103.65	$1,103.75	$1,103.60