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	$112.73	12.715%	$127.0636	$127.06	$127.05	$127.10
Purchase #2	$85.94	9.118%	$93.776	$93.78	$93.80	$93.80
Purchase #3	$34.53	3.413%	$35.7085	$35.71	$35.70	$35.70
Purchase #4	$90.66	4.812%	$95.0226	$95.02	$95.00	$95.00
Purchase #5	$102.32	9.451%	$111.9903	$111.99	$112.00	$112.00
Purchase #6	$176.60	6.492%	$188.0649	$188.06	$188.05	$188.10
Purchase #7	$65.76	9.359%	$71.9145	$71.91	$71.90	$71.90
7 purchase totals =	$668.54		$723.5404	$723.53	$723.50	$723.60