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	$92.61	3.238%	$95.6087	$95.61	$95.60	$95.60
Purchase #2	$211.78	12.275%	$237.776	$237.78	$237.80	$237.80
Purchase #3	$155.44	11.613%	$173.4912	$173.49	$173.50	$173.50
Purchase #4	$250.49	4.387%	$261.479	$261.48	$261.50	$261.50
Purchase #5	$43.88	13.702%	$49.8924	$49.89	$49.90	$49.90
Purchase #6	$92.79	6.755%	$99.058	$99.06	$99.05	$99.10
Purchase #7	$107.96	9.355%	$118.0597	$118.06	$118.05	$118.10
7 purchase totals =	$954.95		$1,035.3650	$1,035.37	$1,035.40	$1,035.50