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	$188.76	6.287%	$200.6273	$200.63	$200.65	$200.60
Purchase #2	$127.79	12.301%	$143.5094	$143.51	$143.50	$143.50
Purchase #3	$147.49	9.552%	$161.5782	$161.58	$161.60	$161.60
Purchase #4	$198.32	10.526%	$219.1952	$219.20	$219.20	$219.20
Purchase #5	$216.76	11.603%	$241.9107	$241.91	$241.90	$241.90
Purchase #6	$41.86	11.605%	$46.7179	$46.72	$46.70	$46.70
Purchase #7	$159.48	7.630%	$171.6483	$171.65	$171.65	$171.60
7 purchase totals =	$1,080.46		$1,185.1870	$1,185.20	$1,185.20	$1,185.10