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	$211.97	4.378%	$221.25	$221.25	$221.25	$221.30
Purchase #2	$52.38	5.460%	$55.2399	$55.24	$55.25	$55.20
Purchase #3	$77.87	6.456%	$82.8973	$82.90	$82.90	$82.90
Purchase #4	$201.70	10.338%	$222.5517	$222.55	$222.55	$222.60
Purchase #5	$119.31	7.466%	$128.2177	$128.22	$128.20	$128.20
Purchase #6	$22.85	9.805%	$25.0904	$25.09	$25.10	$25.10
Purchase #7	$248.84	10.575%	$275.1548	$275.15	$275.15	$275.20
7 purchase totals =	$934.92		$1,010.4018	$1,010.40	$1,010.40	$1,010.50