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	$152.66	4.384%	$159.3526	$159.35	$159.35	$159.40
Purchase #2	$191.29	7.377%	$205.4015	$205.40	$205.40	$205.40
Purchase #3	$41.57	8.342%	$45.0378	$45.04	$45.05	$45.00
Purchase #4	$13.63	8.489%	$14.7871	$14.79	$14.80	$14.80
Purchase #5	$206.71	6.136%	$219.3937	$219.39	$219.40	$219.40
Purchase #6	$139.88	8.827%	$152.2272	$152.23	$152.25	$152.20
Purchase #7	$178.83	9.761%	$196.2856	$196.29	$196.30	$196.30
7 purchase totals =	$924.57		$992.4855	$992.49	$992.55	$992.50