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	$186.39	5.179%	$196.0431	$196.04	$196.05	$196.00
Purchase #2	$128.92	10.545%	$142.5146	$142.51	$142.50	$142.50
Purchase #3	$56.41	6.864%	$60.282	$60.28	$60.30	$60.30
Purchase #4	$186.40	4.846%	$195.4329	$195.43	$195.45	$195.40
Purchase #5	$226.41	5.475%	$238.8059	$238.81	$238.80	$238.80
Purchase #6	$5.25	12.855%	$5.9249	$5.92	$5.90	$5.90
Purchase #7	$164.54	5.561%	$173.6901	$173.69	$173.70	$173.70
7 purchase totals =	$954.32		$1,012.6935	$1,012.68	$1,012.70	$1,012.60