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	$208.32	3.279%	$215.1508	$215.15	$215.15	$215.20
Purchase #2	$80.67	9.181%	$88.0763	$88.08	$88.10	$88.10
Purchase #3	$10.96	13.232%	$12.4102	$12.41	$12.40	$12.40
Purchase #4	$91.51	8.250%	$99.0596	$99.06	$99.05	$99.10
Purchase #5	$171.49	6.274%	$182.2493	$182.25	$182.25	$182.20
Purchase #6	$24.88	9.772%	$27.3113	$27.31	$27.30	$27.30
Purchase #7	$96.86	4.472%	$101.1916	$101.19	$101.20	$101.20
7 purchase totals =	$684.69		$725.4491	$725.45	$725.45	$725.50