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	$182.62	5.476%	$192.6203	$192.62	$192.60	$192.60
Purchase #2	$94.77	13.197%	$107.2768	$107.28	$107.30	$107.30
Purchase #3	$99.29	11.864%	$111.0698	$111.07	$111.05	$111.10
Purchase #4	$62.92	3.681%	$65.2361	$65.24	$65.25	$65.20
Purchase #5	$90.30	10.612%	$99.8826	$99.88	$99.90	$99.90
Purchase #6	$41.26	8.113%	$44.6074	$44.61	$44.60	$44.60
Purchase #7	$90.31	6.338%	$96.0338	$96.03	$96.05	$96.00
7 purchase totals =	$661.47		$716.7268	$716.73	$716.75	$716.70