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	$196.38	13.867%	$223.612	$223.61	$223.60	$223.60
Purchase #2	$70.96	11.215%	$78.9182	$78.92	$78.90	$78.90
Purchase #3	$164.98	3.504%	$170.7609	$170.76	$170.75	$170.80
Purchase #4	$187.53	7.620%	$201.8198	$201.82	$201.80	$201.80
Purchase #5	$161.33	3.604%	$167.1443	$167.14	$167.15	$167.10
Purchase #6	$133.90	4.354%	$139.73	$139.73	$139.75	$139.70
Purchase #7	$249.50	7.629%	$268.5344	$268.53	$268.55	$268.50
7 purchase totals =	$1,164.58		$1,250.5196	$1,250.51	$1,250.50	$1,250.40