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	$181.83	7.799%	$196.0109	$196.01	$196.00	$196.00
Purchase #2	$174.44	12.580%	$196.3846	$196.38	$196.40	$196.40
Purchase #3	$98.85	8.569%	$107.3205	$107.32	$107.30	$107.30
Purchase #4	$135.82	13.676%	$154.3947	$154.39	$154.40	$154.40
Purchase #5	$71.92	8.717%	$78.1893	$78.19	$78.20	$78.20
Purchase #6	$27.88	3.209%	$28.7747	$28.77	$28.75	$28.80
Purchase #7	$181.37	5.351%	$191.0751	$191.08	$191.10	$191.10
7 purchase totals =	$872.11		$952.1498	$952.14	$952.15	$952.20