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	$141.84	11.120%	$157.6126	$157.61	$157.60	$157.60
Purchase #2	$77.42	9.276%	$84.6015	$84.60	$84.60	$84.60
Purchase #3	$166.35	13.293%	$188.4629	$188.46	$188.45	$188.50
Purchase #4	$178.45	10.142%	$196.5484	$196.55	$196.55	$196.50
Purchase #5	$127.30	9.294%	$139.1313	$139.13	$139.15	$139.10
Purchase #6	$181.94	7.478%	$195.5455	$195.55	$195.55	$195.50
Purchase #7	$67.81	8.395%	$73.5026	$73.50	$73.50	$73.50
7 purchase totals =	$941.11		$1,035.4048	$1,035.40	$1,035.40	$1,035.30