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	$157.74	7.535%	$169.6257	$169.63	$169.65	$169.60
Purchase #2	$140.30	5.388%	$147.8594	$147.86	$147.85	$147.90
Purchase #3	$42.30	7.536%	$45.4877	$45.49	$45.50	$45.50
Purchase #4	$81.72	5.666%	$86.3503	$86.35	$86.35	$86.40
Purchase #5	$139.83	10.416%	$154.3947	$154.39	$154.40	$154.40
Purchase #6	$11.99	7.388%	$12.8758	$12.88	$12.90	$12.90
Purchase #7	$147.92	5.860%	$156.5881	$156.59	$156.60	$156.60
7 purchase totals =	$721.80		$773.1817	$773.19	$773.25	$773.30