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	$185.80	5.859%	$196.686	$196.69	$196.70	$196.70
Purchase #2	$113.30	12.524%	$127.4897	$127.49	$127.50	$127.50
Purchase #3	$215.75	10.709%	$238.8547	$238.85	$238.85	$238.90
Purchase #4	$155.60	11.723%	$173.841	$173.84	$173.85	$173.80
Purchase #5	$219.88	9.122%	$239.9375	$239.94	$239.95	$239.90
Purchase #6	$175.32	3.719%	$181.8402	$181.84	$181.85	$181.80
Purchase #7	$30.53	9.313%	$33.3733	$33.37	$33.35	$33.40
7 purchase totals =	$1,096.18		$1,192.0224	$1,192.02	$1,192.05	$1,192.00