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	$13.34	7.786%	$14.3787	$14.38	$14.40	$14.40
Purchase #2	$224.81	8.846%	$244.6967	$244.70	$244.70	$244.70
Purchase #3	$50.54	9.592%	$55.3878	$55.39	$55.40	$55.40
Purchase #4	$120.38	9.481%	$131.7932	$131.79	$131.80	$131.80
Purchase #5	$136.30	10.717%	$150.9073	$150.91	$150.90	$150.90
Purchase #6	$227.58	7.751%	$245.2197	$245.22	$245.20	$245.20
Purchase #7	$205.74	6.291%	$218.6831	$218.68	$218.70	$218.70
7 purchase totals =	$978.69		$1,061.0665	$1,061.07	$1,061.10	$1,061.10