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	$130.41	10.240%	$143.764	$143.76	$143.75	$143.80
Purchase #2	$62.34	9.439%	$68.2243	$68.22	$68.20	$68.20
Purchase #3	$134.74	4.254%	$140.4718	$140.47	$140.45	$140.50
Purchase #4	$242.74	7.481%	$260.8994	$260.90	$260.90	$260.90
Purchase #5	$188.57	4.396%	$196.8595	$196.86	$196.85	$196.90
Purchase #6	$178.77	4.866%	$187.4689	$187.47	$187.45	$187.50
Purchase #7	$68.27	6.261%	$72.5444	$72.54	$72.55	$72.50
7 purchase totals =	$1,005.84		$1,070.2323	$1,070.22	$1,070.15	$1,070.30