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	$196.50	6.119%	$208.5238	$208.52	$208.50	$208.50
Purchase #2	$39.55	9.595%	$43.3448	$43.34	$43.35	$43.30
Purchase #3	$92.74	7.193%	$99.4108	$99.41	$99.40	$99.40
Purchase #4	$221.77	11.613%	$247.5242	$247.52	$247.50	$247.50
Purchase #5	$163.43	6.275%	$173.6852	$173.69	$173.70	$173.70
Purchase #6	$93.34	5.587%	$98.5549	$98.55	$98.55	$98.60
Purchase #7	$9.48	10.478%	$10.4733	$10.47	$10.45	$10.50
7 purchase totals =	$816.81		$881.5170	$881.50	$881.45	$881.50