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	$115.57	9.862%	$126.9675	$126.97	$126.95	$127.00
Purchase #2	$229.89	7.678%	$247.541	$247.54	$247.55	$247.50
Purchase #3	$60.96	12.167%	$68.377	$68.38	$68.40	$68.40
Purchase #4	$147.37	8.661%	$160.1337	$160.13	$160.15	$160.10
Purchase #5	$117.25	12.169%	$131.5182	$131.52	$131.50	$131.50
Purchase #6	$220.68	8.276%	$238.9435	$238.94	$238.95	$238.90
Purchase #7	$201.57	10.657%	$223.0513	$223.05	$223.05	$223.10
7 purchase totals =	$1,093.29		$1,196.5322	$1,196.53	$1,196.55	$1,196.50