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	$108.71	8.512%	$117.9634	$117.96	$117.95	$118.00
Purchase #2	$168.35	5.762%	$178.0503	$178.05	$178.05	$178.10
Purchase #3	$175.55	6.554%	$187.0555	$187.06	$187.05	$187.10
Purchase #4	$98.67	7.211%	$105.7851	$105.79	$105.80	$105.80
Purchase #5	$201.94	11.498%	$225.1591	$225.16	$225.15	$225.20
Purchase #6	$104.57	6.450%	$111.3148	$111.31	$111.30	$111.30
Purchase #7	$89.94	11.604%	$100.3766	$100.38	$100.40	$100.40
7 purchase totals =	$947.73		$1,025.7048	$1,025.71	$1,025.70	$1,025.90