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	$88.95	3.449%	$92.0179	$92.02	$92.00	$92.00
Purchase #2	$218.97	7.412%	$235.2001	$235.20	$235.20	$235.20
Purchase #3	$40.43	4.182%	$42.1208	$42.12	$42.10	$42.10
Purchase #4	$207.39	7.341%	$222.6145	$222.61	$222.60	$222.60
Purchase #5	$72.28	13.593%	$82.105	$82.11	$82.10	$82.10
Purchase #6	$160.67	5.513%	$169.5277	$169.53	$169.55	$169.50
Purchase #7	$250.69	12.851%	$282.9062	$282.91	$282.90	$282.90
7 purchase totals =	$1,039.38		$1,126.4922	$1,126.50	$1,126.45	$1,126.40