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	$147.32	3.342%	$152.2434	$152.24	$152.25	$152.20
Purchase #2	$92.83	4.273%	$96.7966	$96.80	$96.80	$96.80
Purchase #3	$155.36	6.151%	$164.9162	$164.92	$164.90	$164.90
Purchase #4	$95.80	3.165%	$98.8321	$98.83	$98.85	$98.80
Purchase #5	$160.53	9.608%	$175.9537	$175.95	$175.95	$176.00
Purchase #6	$112.59	12.466%	$126.6255	$126.63	$126.65	$126.60
Purchase #7	$198.78	8.459%	$215.5948	$215.59	$215.60	$215.60
7 purchase totals =	$963.21		$1,030.9623	$1,030.96	$1,031.00	$1,030.90