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	$233.75	7.209%	$250.601	$250.60	$250.60	$250.60
Purchase #2	$242.32	8.515%	$262.9535	$262.95	$262.95	$263.00
Purchase #3	$104.29	10.358%	$115.0924	$115.09	$115.10	$115.10
Purchase #4	$178.46	3.554%	$184.8025	$184.80	$184.80	$184.80
Purchase #5	$109.76	13.782%	$124.8871	$124.89	$124.90	$124.90
Purchase #6	$198.42	12.300%	$222.8257	$222.83	$222.85	$222.80
Purchase #7	$153.89	11.751%	$171.9736	$171.97	$171.95	$172.00
7 purchase totals =	$1,220.89		$1,333.1358	$1,333.13	$1,333.15	$1,333.20