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	$195.92	7.273%	$210.1693	$210.17	$210.15	$210.20
Purchase #2	$98.92	12.592%	$111.376	$111.38	$111.40	$111.40
Purchase #3	$32.89	11.815%	$36.776	$36.78	$36.80	$36.80
Purchase #4	$148.81	10.778%	$164.8487	$164.85	$164.85	$164.80
Purchase #5	$151.84	10.204%	$167.3338	$167.33	$167.35	$167.30
Purchase #6	$188.32	4.595%	$196.9733	$196.97	$196.95	$197.00
Purchase #7	$14.32	4.683%	$14.9906	$14.99	$15.00	$15.00
7 purchase totals =	$831.02		$902.4677	$902.47	$902.50	$902.50