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	$242.94	7.449%	$261.0366	$261.04	$261.05	$261.00
Purchase #2	$250.45	6.255%	$266.1156	$266.12	$266.10	$266.10
Purchase #3	$7.30	3.749%	$7.5737	$7.57	$7.55	$7.60
Purchase #4	$181.44	8.544%	$196.9422	$196.94	$196.95	$196.90
Purchase #5	$101.53	3.796%	$105.3841	$105.38	$105.40	$105.40
Purchase #6	$149.61	3.743%	$155.2099	$155.21	$155.20	$155.20
Purchase #7	$145.40	3.325%	$150.2346	$150.23	$150.25	$150.20
7 purchase totals =	$1,078.67		$1,142.4967	$1,142.49	$1,142.50	$1,142.40