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	$241.59	9.868%	$265.4301	$265.43	$265.45	$265.40
Purchase #2	$187.89	12.726%	$211.8009	$211.80	$211.80	$211.80
Purchase #3	$57.86	12.624%	$65.1642	$65.16	$65.15	$65.20
Purchase #4	$150.50	4.244%	$156.8872	$156.89	$156.90	$156.90
Purchase #5	$176.49	7.796%	$190.2492	$190.25	$190.25	$190.20
Purchase #6	$26.87	8.824%	$29.241	$29.24	$29.25	$29.20
Purchase #7	$84.91	12.719%	$95.7097	$95.71	$95.70	$95.70
7 purchase totals =	$926.11		$1,014.4823	$1,014.48	$1,014.50	$1,014.40