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	$99.26	10.254%	$109.4381	$109.44	$109.45	$109.40
Purchase #2	$32.74	12.480%	$36.826	$36.83	$36.85	$36.80
Purchase #3	$223.84	11.617%	$249.8435	$249.84	$249.85	$249.80
Purchase #4	$213.31	8.360%	$231.1427	$231.14	$231.15	$231.10
Purchase #5	$157.42	11.496%	$175.517	$175.52	$175.50	$175.50
Purchase #6	$143.94	3.416%	$148.857	$148.86	$148.85	$148.90
Purchase #7	$176.60	12.362%	$198.4313	$198.43	$198.45	$198.40
7 purchase totals =	$1,047.11		$1,150.0556	$1,150.06	$1,150.10	$1,149.90