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	$137.28	11.254%	$152.7295	$152.73	$152.75	$152.70
Purchase #2	$118.96	7.507%	$127.8903	$127.89	$127.90	$127.90
Purchase #3	$240.54	10.518%	$265.84	$265.84	$265.85	$265.80
Purchase #4	$76.92	7.378%	$82.5952	$82.60	$82.60	$82.60
Purchase #5	$97.32	6.442%	$103.5894	$103.59	$103.60	$103.60
Purchase #6	$122.72	10.402%	$135.4853	$135.49	$135.50	$135.50
Purchase #7	$175.88	8.267%	$190.42	$190.42	$190.40	$190.40
7 purchase totals =	$969.62		$1,058.5497	$1,058.56	$1,058.60	$1,058.50