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	$191.65	3.352%	$198.0741	$198.07	$198.05	$198.10
Purchase #2	$114.53	11.564%	$127.7742	$127.77	$127.75	$127.80
Purchase #3	$25.47	9.684%	$27.9365	$27.94	$27.95	$27.90
Purchase #4	$71.61	3.219%	$73.9151	$73.92	$73.90	$73.90
Purchase #5	$238.59	12.252%	$267.822	$267.82	$267.80	$267.80
Purchase #6	$241.42	5.736%	$255.2679	$255.27	$255.25	$255.30
Purchase #7	$58.38	9.617%	$63.9944	$63.99	$64.00	$64.00
7 purchase totals =	$941.65		$1,014.7842	$1,014.78	$1,014.70	$1,014.80