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	$108.89	4.442%	$113.7269	$113.73	$113.75	$113.70
Purchase #2	$150.77	7.116%	$161.4988	$161.50	$161.50	$161.50
Purchase #3	$156.45	11.676%	$174.7171	$174.72	$174.70	$174.70
Purchase #4	$198.67	12.452%	$223.4084	$223.41	$223.40	$223.40
Purchase #5	$30.61	7.670%	$32.9578	$32.96	$32.95	$33.00
Purchase #6	$124.42	9.709%	$136.4999	$136.50	$136.50	$136.50
Purchase #7	$126.35	4.122%	$131.5581	$131.56	$131.55	$131.60
7 purchase totals =	$896.16		$974.3670	$974.38	$974.35	$974.40