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	$173.60	7.872%	$187.2658	$187.27	$187.25	$187.30
Purchase #2	$185.41	3.163%	$191.2745	$191.27	$191.25	$191.30
Purchase #3	$157.47	8.696%	$171.1636	$171.16	$171.15	$171.20
Purchase #4	$198.90	13.665%	$226.0797	$226.08	$226.10	$226.10
Purchase #5	$67.72	5.287%	$71.3004	$71.30	$71.30	$71.30
Purchase #6	$192.35	13.219%	$217.7767	$217.78	$217.80	$217.80
Purchase #7	$120.95	5.558%	$127.6724	$127.67	$127.65	$127.70
7 purchase totals =	$1,096.40		$1,192.5331	$1,192.53	$1,192.50	$1,192.70