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	$106.96	9.265%	$116.8698	$116.87	$116.85	$116.90
Purchase #2	$154.85	3.349%	$160.0359	$160.04	$160.05	$160.00
Purchase #3	$195.46	6.366%	$207.903	$207.90	$207.90	$207.90
Purchase #4	$244.64	7.855%	$263.8565	$263.86	$263.85	$263.90
Purchase #5	$109.93	12.516%	$123.6888	$123.69	$123.70	$123.70
Purchase #6	$41.58	10.390%	$45.9002	$45.90	$45.90	$45.90
Purchase #7	$127.96	6.728%	$136.5691	$136.57	$136.55	$136.60
7 purchase totals =	$981.38		$1,054.8233	$1,054.83	$1,054.80	$1,054.90