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	$182.74	9.697%	$200.4603	$200.46	$200.45	$200.50
Purchase #2	$181.79	3.475%	$188.1072	$188.11	$188.10	$188.10
Purchase #3	$5.97	5.681%	$6.3092	$6.31	$6.30	$6.30
Purchase #4	$6.78	10.616%	$7.4998	$7.50	$7.50	$7.50
Purchase #5	$105.75	3.595%	$109.5517	$109.55	$109.55	$109.60
Purchase #6	$157.97	9.294%	$172.6517	$172.65	$172.65	$172.70
Purchase #7	$134.84	12.666%	$151.9188	$151.92	$151.90	$151.90
7 purchase totals =	$775.84		$836.4987	$836.50	$836.45	$836.60