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	$160.78	11.115%	$178.6507	$178.65	$178.65	$178.70
Purchase #2	$246.89	3.634%	$255.862	$255.86	$255.85	$255.90
Purchase #3	$104.98	8.515%	$113.919	$113.92	$113.90	$113.90
Purchase #4	$62.35	6.687%	$66.5193	$66.52	$66.50	$66.50
Purchase #5	$148.30	3.802%	$153.9384	$153.94	$153.95	$153.90
Purchase #6	$128.66	3.148%	$132.7102	$132.71	$132.70	$132.70
Purchase #7	$157.59	4.470%	$164.6343	$164.63	$164.65	$164.60
7 purchase totals =	$1,009.55		$1,066.2339	$1,066.23	$1,066.20	$1,066.20