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	$176.44	9.143%	$192.5719	$192.57	$192.55	$192.60
Purchase #2	$18.26	12.607%	$20.562	$20.56	$20.55	$20.60
Purchase #3	$62.59	4.824%	$65.6093	$65.61	$65.60	$65.60
Purchase #4	$232.78	3.315%	$240.4967	$240.50	$240.50	$240.50
Purchase #5	$229.32	4.636%	$239.9513	$239.95	$239.95	$240.00
Purchase #6	$244.81	6.810%	$261.4816	$261.48	$261.50	$261.50
Purchase #7	$87.61	3.815%	$90.9523	$90.95	$90.95	$91.00
7 purchase totals =	$1,051.81		$1,111.6251	$1,111.62	$1,111.60	$1,111.80