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	$195.37	9.187%	$213.3186	$213.32	$213.30	$213.30
Purchase #2	$114.62	11.204%	$127.462	$127.46	$127.45	$127.50
Purchase #3	$10.54	7.554%	$11.3362	$11.34	$11.35	$11.30
Purchase #4	$171.53	4.608%	$179.4341	$179.43	$179.45	$179.40
Purchase #5	$80.95	5.214%	$85.1707	$85.17	$85.15	$85.20
Purchase #6	$140.98	6.589%	$150.2692	$150.27	$150.25	$150.30
Purchase #7	$242.98	10.703%	$268.9861	$268.99	$269.00	$269.00
7 purchase totals =	$956.97		$1,035.9769	$1,035.98	$1,035.95	$1,036.00