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	$127.59	11.837%	$142.6928	$142.69	$142.70	$142.70
Purchase #2	$115.61	9.154%	$126.1929	$126.19	$126.20	$126.20
Purchase #3	$113.45	13.301%	$128.54	$128.54	$128.55	$128.50
Purchase #4	$89.64	9.815%	$98.4382	$98.44	$98.45	$98.40
Purchase #5	$156.31	9.616%	$171.3408	$171.34	$171.35	$171.30
Purchase #6	$193.56	7.168%	$207.4344	$207.43	$207.45	$207.40
Purchase #7	$179.66	11.617%	$200.5311	$200.53	$200.55	$200.50
7 purchase totals =	$975.82		$1,075.1702	$1,075.16	$1,075.25	$1,075.00