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	$80.45	7.439%	$86.4347	$86.43	$86.45	$86.40
Purchase #2	$171.88	8.534%	$186.5482	$186.55	$186.55	$186.50
Purchase #3	$33.79	9.279%	$36.9254	$36.93	$36.95	$36.90
Purchase #4	$223.83	13.718%	$254.535	$254.54	$254.55	$254.50
Purchase #5	$221.85	12.556%	$249.7055	$249.71	$249.70	$249.70
Purchase #6	$202.86	4.857%	$212.7129	$212.71	$212.70	$212.70
Purchase #7	$152.78	11.160%	$169.8302	$169.83	$169.85	$169.80
7 purchase totals =	$1,087.44		$1,196.6919	$1,196.70	$1,196.75	$1,196.50