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	$214.31	4.505%	$223.9647	$223.96	$223.95	$224.00
Purchase #2	$172.53	13.608%	$196.0079	$196.01	$196.00	$196.00
Purchase #3	$41.26	12.382%	$46.3688	$46.37	$46.35	$46.40
Purchase #4	$76.74	13.406%	$87.0278	$87.03	$87.05	$87.00
Purchase #5	$119.50	6.626%	$127.4181	$127.42	$127.40	$127.40
Purchase #6	$175.55	12.216%	$196.9952	$197.00	$197.00	$197.00
Purchase #7	$115.46	7.803%	$124.4693	$124.47	$124.45	$124.50
7 purchase totals =	$915.35		$1,002.2518	$1,002.26	$1,002.20	$1,002.30