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	$119.40	11.796%	$133.4844	$133.48	$133.50	$133.50
Purchase #2	$13.26	12.676%	$14.9408	$14.94	$14.95	$14.90
Purchase #3	$143.56	11.743%	$160.4183	$160.42	$160.40	$160.40
Purchase #4	$40.75	11.832%	$45.5715	$45.57	$45.55	$45.60
Purchase #5	$57.50	4.239%	$59.9374	$59.94	$59.95	$59.90
Purchase #6	$68.85	3.154%	$71.0215	$71.02	$71.00	$71.00
Purchase #7	$213.71	13.778%	$243.155	$243.16	$243.15	$243.20
7 purchase totals =	$657.03		$728.5289	$728.53	$728.50	$728.50