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	$82.54	3.711%	$85.6031	$85.60	$85.60	$85.60
Purchase #2	$11.61	13.214%	$13.1441	$13.14	$13.15	$13.10
Purchase #3	$127.77	6.853%	$136.5261	$136.53	$136.55	$136.50
Purchase #4	$148.26	5.302%	$156.1207	$156.12	$156.10	$156.10
Purchase #5	$111.89	10.473%	$123.6082	$123.61	$123.60	$123.60
Purchase #6	$223.78	5.150%	$235.3047	$235.30	$235.30	$235.30
Purchase #7	$115.42	9.362%	$126.2256	$126.23	$126.25	$126.20
7 purchase totals =	$821.27		$876.5325	$876.53	$876.55	$876.40