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	$212.67	13.377%	$241.1189	$241.12	$241.10	$241.10
Purchase #2	$132.87	3.289%	$137.2401	$137.24	$137.25	$137.20
Purchase #3	$158.48	7.223%	$169.927	$169.93	$169.95	$169.90
Purchase #4	$159.37	4.811%	$167.0373	$167.04	$167.05	$167.00
Purchase #5	$156.60	5.292%	$164.8873	$164.89	$164.90	$164.90
Purchase #6	$105.54	4.653%	$110.4508	$110.45	$110.45	$110.50
Purchase #7	$80.26	4.539%	$83.903	$83.90	$83.90	$83.90
7 purchase totals =	$1,005.79		$1,074.5644	$1,074.57	$1,074.60	$1,074.50