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	$55.66	11.299%	$61.949	$61.95	$61.95	$61.90
Purchase #2	$34.95	7.639%	$37.6198	$37.62	$37.60	$37.60
Purchase #3	$163.76	8.700%	$178.0071	$178.01	$178.00	$178.00
Purchase #4	$96.25	3.820%	$99.9268	$99.93	$99.95	$99.90
Purchase #5	$145.44	13.734%	$165.4147	$165.41	$165.40	$165.40
Purchase #6	$250.65	4.572%	$262.1097	$262.11	$262.10	$262.10
Purchase #7	$39.66	13.369%	$44.9621	$44.96	$44.95	$45.00
7 purchase totals =	$786.37		$849.9892	$849.99	$849.95	$849.90