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	$65.46	3.319%	$67.6326	$67.63	$67.65	$67.60
Purchase #2	$16.86	8.430%	$18.2813	$18.28	$18.30	$18.30
Purchase #3	$153.25	7.249%	$164.3591	$164.36	$164.35	$164.40
Purchase #4	$112.52	13.323%	$127.511	$127.51	$127.50	$127.50
Purchase #5	$181.56	5.438%	$191.4332	$191.43	$191.45	$191.40
Purchase #6	$12.57	6.274%	$13.3586	$13.36	$13.35	$13.40
Purchase #7	$213.32	4.626%	$223.1882	$223.19	$223.20	$223.20
7 purchase totals =	$755.54		$805.7640	$805.76	$805.80	$805.80