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	$98.83	13.131%	$111.8074	$111.81	$111.80	$111.80
Purchase #2	$105.48	5.641%	$111.4301	$111.43	$111.45	$111.40
Purchase #3	$42.41	3.806%	$44.0241	$44.02	$44.00	$44.00
Purchase #4	$62.77	3.846%	$65.1841	$65.18	$65.20	$65.20
Purchase #5	$52.61	12.789%	$59.3383	$59.34	$59.35	$59.30
Purchase #6	$209.79	3.760%	$217.6781	$217.68	$217.70	$217.70
Purchase #7	$143.75	6.273%	$152.7674	$152.77	$152.75	$152.80
7 purchase totals =	$715.64		$762.2295	$762.23	$762.25	$762.20