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	$161.81	7.779%	$174.3972	$174.40	$174.40	$174.40
Purchase #2	$197.82	7.678%	$213.0086	$213.01	$213.00	$213.00
Purchase #3	$28.65	12.543%	$32.2436	$32.24	$32.25	$32.20
Purchase #4	$211.43	5.620%	$223.3124	$223.31	$223.30	$223.30
Purchase #5	$153.29	12.480%	$172.4206	$172.42	$172.40	$172.40
Purchase #6	$173.56	7.778%	$187.0595	$187.06	$187.05	$187.10
Purchase #7	$89.67	5.476%	$94.5803	$94.58	$94.60	$94.60
7 purchase totals =	$1,016.23		$1,097.0222	$1,097.02	$1,097.00	$1,097.00