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	$98.64	13.499%	$111.9554	$111.96	$111.95	$112.00
Purchase #2	$118.55	8.318%	$128.411	$128.41	$128.40	$128.40
Purchase #3	$171.49	6.597%	$182.8032	$182.80	$182.80	$182.80
Purchase #4	$5.57	8.785%	$6.0593	$6.06	$6.05	$6.10
Purchase #5	$53.83	3.289%	$55.6005	$55.60	$55.60	$55.60
Purchase #6	$185.50	5.713%	$196.0976	$196.10	$196.10	$196.10
Purchase #7	$30.83	9.778%	$33.8446	$33.84	$33.85	$33.80
7 purchase totals =	$664.41		$714.7716	$714.77	$714.75	$714.80