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	$241.89	9.382%	$264.5841	$264.58	$264.60	$264.60
Purchase #2	$228.96	10.753%	$253.5801	$253.58	$253.60	$253.60
Purchase #3	$80.76	7.463%	$86.7871	$86.79	$86.80	$86.80
Purchase #4	$170.50	10.124%	$187.7614	$187.76	$187.75	$187.80
Purchase #5	$28.99	11.134%	$32.2177	$32.22	$32.20	$32.20
Purchase #6	$173.81	13.688%	$197.6011	$197.60	$197.60	$197.60
Purchase #7	$28.92	10.254%	$31.8855	$31.89	$31.90	$31.90
7 purchase totals =	$953.83		$1,054.4170	$1,054.42	$1,054.45	$1,054.50