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	$108.82	4.668%	$113.8997	$113.90	$113.90	$113.90
Purchase #2	$97.64	6.374%	$103.8636	$103.86	$103.85	$103.90
Purchase #3	$145.86	6.714%	$155.653	$155.65	$155.65	$155.70
Purchase #4	$151.37	12.667%	$170.544	$170.54	$170.55	$170.50
Purchase #5	$178.78	12.418%	$200.9809	$200.98	$201.00	$201.00
Purchase #6	$92.69	6.682%	$98.8835	$98.88	$98.90	$98.90
Purchase #7	$161.67	9.182%	$176.5145	$176.51	$176.50	$176.50
7 purchase totals =	$936.83		$1,020.3392	$1,020.32	$1,020.35	$1,020.40