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	$13.42	7.353%	$14.4068	$14.41	$14.40	$14.40
Purchase #2	$246.52	7.365%	$264.6762	$264.68	$264.70	$264.70
Purchase #3	$170.44	11.651%	$190.298	$190.30	$190.30	$190.30
Purchase #4	$141.62	6.550%	$150.8961	$150.90	$150.90	$150.90
Purchase #5	$216.98	12.705%	$244.5473	$244.55	$244.55	$244.50
Purchase #6	$192.89	13.585%	$219.0941	$219.09	$219.10	$219.10
Purchase #7	$146.60	13.867%	$166.929	$166.93	$166.95	$166.90
7 purchase totals =	$1,128.47		$1,250.8475	$1,250.86	$1,250.90	$1,250.80