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	$98.41	7.493%	$105.7839	$105.78	$105.80	$105.80
Purchase #2	$14.36	8.274%	$15.5481	$15.55	$15.55	$15.50
Purchase #3	$189.53	12.210%	$212.6716	$212.67	$212.65	$212.70
Purchase #4	$227.92	6.851%	$243.5348	$243.53	$243.55	$243.50
Purchase #5	$203.43	9.776%	$223.3173	$223.32	$223.30	$223.30
Purchase #6	$46.94	6.311%	$49.9024	$49.90	$49.90	$49.90
Purchase #7	$154.57	11.208%	$171.8942	$171.89	$171.90	$171.90
7 purchase totals =	$935.16		$1,022.6523	$1,022.64	$1,022.65	$1,022.60