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	$91.71	5.713%	$96.9494	$96.95	$96.95	$96.90
Purchase #2	$196.52	11.661%	$219.4362	$219.44	$219.45	$219.40
Purchase #3	$34.90	4.768%	$36.564	$36.56	$36.55	$36.60
Purchase #4	$230.84	3.178%	$238.1761	$238.18	$238.20	$238.20
Purchase #5	$234.43	7.140%	$251.1683	$251.17	$251.15	$251.20
Purchase #6	$33.25	13.693%	$37.8029	$37.80	$37.80	$37.80
Purchase #7	$194.92	5.641%	$205.9154	$205.92	$205.90	$205.90
7 purchase totals =	$1,016.57		$1,086.0123	$1,086.02	$1,086.00	$1,086.00