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	$197.31	11.134%	$219.2785	$219.28	$219.30	$219.30
Purchase #2	$230.29	11.363%	$256.4579	$256.46	$256.45	$256.50
Purchase #3	$51.42	7.443%	$55.2472	$55.25	$55.25	$55.20
Purchase #4	$138.94	10.712%	$153.8233	$153.82	$153.80	$153.80
Purchase #5	$97.75	11.836%	$109.3197	$109.32	$109.30	$109.30
Purchase #6	$92.83	5.689%	$98.1111	$98.11	$98.10	$98.10
Purchase #7	$145.70	13.689%	$165.6449	$165.64	$165.65	$165.60
7 purchase totals =	$954.24		$1,057.8826	$1,057.88	$1,057.85	$1,057.80