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	$147.89	4.375%	$154.3602	$154.36	$154.35	$154.40
Purchase #2	$136.84	4.444%	$142.9212	$142.92	$142.90	$142.90
Purchase #3	$171.61	8.726%	$186.5847	$186.58	$186.60	$186.60
Purchase #4	$79.30	12.591%	$89.2847	$89.28	$89.30	$89.30
Purchase #5	$186.53	11.823%	$208.5834	$208.58	$208.60	$208.60
Purchase #6	$5.86	8.109%	$6.3352	$6.34	$6.35	$6.30
Purchase #7	$236.69	8.774%	$257.4572	$257.46	$257.45	$257.50
7 purchase totals =	$964.72		$1,045.5266	$1,045.52	$1,045.55	$1,045.60