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	$172.69	8.335%	$187.0837	$187.08	$187.10	$187.10
Purchase #2	$79.69	12.481%	$89.6361	$89.64	$89.65	$89.60
Purchase #3	$61.32	7.521%	$65.9319	$65.93	$65.95	$65.90
Purchase #4	$236.64	10.686%	$261.9274	$261.93	$261.95	$261.90
Purchase #5	$231.31	6.756%	$246.9373	$246.94	$246.95	$246.90
Purchase #6	$45.88	3.738%	$47.595	$47.60	$47.60	$47.60
Purchase #7	$147.34	10.492%	$162.7989	$162.80	$162.80	$162.80
7 purchase totals =	$974.87		$1,061.9103	$1,061.92	$1,062.00	$1,061.80