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	$241.90	8.185%	$261.6995	$261.70	$261.70	$261.70
Purchase #2	$126.62	13.360%	$143.5364	$143.54	$143.55	$143.50
Purchase #3	$94.57	7.411%	$101.5786	$101.58	$101.60	$101.60
Purchase #4	$98.36	11.427%	$109.5996	$109.60	$109.60	$109.60
Purchase #5	$141.85	9.609%	$155.4804	$155.48	$155.50	$155.50
Purchase #6	$78.82	9.519%	$86.3229	$86.32	$86.30	$86.30
Purchase #7	$148.98	11.680%	$166.3809	$166.38	$166.40	$166.40
7 purchase totals =	$931.10		$1,024.5983	$1,024.60	$1,024.65	$1,024.60