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	$101.96	7.264%	$109.3664	$109.37	$109.35	$109.40
Purchase #2	$169.73	7.782%	$182.9384	$182.94	$182.95	$182.90
Purchase #3	$162.90	11.493%	$181.6221	$181.62	$181.60	$181.60
Purchase #4	$196.64	10.820%	$217.9164	$217.92	$217.90	$217.90
Purchase #5	$56.25	11.797%	$62.8858	$62.89	$62.90	$62.90
Purchase #6	$156.95	6.570%	$167.2616	$167.26	$167.25	$167.30
Purchase #7	$116.39	7.771%	$125.4347	$125.43	$125.45	$125.40
7 purchase totals =	$960.82		$1,047.4254	$1,047.43	$1,047.40	$1,047.40