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	$114.27	9.484%	$125.1074	$125.11	$125.10	$125.10
Purchase #2	$103.83	10.350%	$114.5764	$114.58	$114.60	$114.60
Purchase #3	$39.33	11.661%	$43.9163	$43.92	$43.90	$43.90
Purchase #4	$26.51	5.388%	$27.9384	$27.94	$27.95	$27.90
Purchase #5	$158.41	12.442%	$178.1194	$178.12	$178.10	$178.10
Purchase #6	$114.25	4.492%	$119.3821	$119.38	$119.40	$119.40
Purchase #7	$116.29	12.194%	$130.4704	$130.47	$130.45	$130.50
7 purchase totals =	$672.89		$739.5104	$739.52	$739.50	$739.50