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	$37.42	7.181%	$40.1071	$40.11	$40.10	$40.10
Purchase #2	$122.86	6.830%	$131.2513	$131.25	$131.25	$131.30
Purchase #3	$12.50	12.840%	$14.105	$14.11	$14.10	$14.10
Purchase #4	$87.74	5.490%	$92.5569	$92.56	$92.55	$92.60
Purchase #5	$116.63	6.464%	$124.169	$124.17	$124.15	$124.20
Purchase #6	$208.74	4.386%	$217.8953	$217.90	$217.90	$217.90
Purchase #7	$72.62	13.312%	$82.2872	$82.29	$82.30	$82.30
7 purchase totals =	$658.51		$702.3718	$702.39	$702.35	$702.50