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	$164.59	4.643%	$172.2319	$172.23	$172.25	$172.20
Purchase #2	$92.35	9.326%	$100.9626	$100.96	$100.95	$101.00
Purchase #3	$117.27	5.599%	$123.8359	$123.84	$123.85	$123.80
Purchase #4	$181.88	8.304%	$196.9833	$196.98	$197.00	$197.00
Purchase #5	$114.31	7.642%	$123.0456	$123.05	$123.05	$123.00
Purchase #6	$247.40	10.648%	$273.7432	$273.74	$273.75	$273.70
Purchase #7	$146.83	6.357%	$156.164	$156.16	$156.15	$156.20
7 purchase totals =	$1,064.63		$1,146.9665	$1,146.96	$1,147.00	$1,146.90