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	$118.57	13.378%	$134.4323	$134.43	$134.45	$134.40
Purchase #2	$10.40	8.830%	$11.3183	$11.32	$11.30	$11.30
Purchase #3	$140.91	8.532%	$152.9324	$152.93	$152.95	$152.90
Purchase #4	$180.93	3.592%	$187.429	$187.43	$187.45	$187.40
Purchase #5	$193.52	12.152%	$217.0366	$217.04	$217.05	$217.00
Purchase #6	$41.33	3.458%	$42.7592	$42.76	$42.75	$42.80
Purchase #7	$51.90	7.147%	$55.6093	$55.61	$55.60	$55.60
7 purchase totals =	$737.56		$801.5171	$801.52	$801.55	$801.40