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	$106.98	11.501%	$119.2838	$119.28	$119.30	$119.30
Purchase #2	$108.85	13.510%	$123.5556	$123.56	$123.55	$123.60
Purchase #3	$193.36	3.652%	$200.4215	$200.42	$200.40	$200.40
Purchase #4	$33.96	7.589%	$36.5372	$36.54	$36.55	$36.50
Purchase #5	$224.47	9.788%	$246.4411	$246.44	$246.45	$246.40
Purchase #6	$59.63	11.244%	$66.3348	$66.33	$66.35	$66.30
Purchase #7	$195.43	6.869%	$208.8541	$208.85	$208.85	$208.90
7 purchase totals =	$922.68		$1,001.4281	$1,001.42	$1,001.45	$1,001.40