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	$197.93	7.676%	$213.1231	$213.12	$213.10	$213.10
Purchase #2	$79.52	10.527%	$87.8911	$87.89	$87.90	$87.90
Purchase #3	$75.32	9.598%	$82.5492	$82.55	$82.55	$82.50
Purchase #4	$227.85	11.713%	$254.5381	$254.54	$254.55	$254.50
Purchase #5	$179.70	4.871%	$188.4532	$188.45	$188.45	$188.50
Purchase #6	$171.66	7.456%	$184.459	$184.46	$184.45	$184.50
Purchase #7	$53.61	13.840%	$61.0296	$61.03	$61.05	$61.00
7 purchase totals =	$985.59		$1,072.0433	$1,072.04	$1,072.05	$1,072.00