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	$97.44	10.378%	$107.5523	$107.55	$107.55	$107.60
Purchase #2	$191.41	11.661%	$213.7303	$213.73	$213.75	$213.70
Purchase #3	$151.33	3.673%	$156.8884	$156.89	$156.90	$156.90
Purchase #4	$239.60	6.611%	$255.44	$255.44	$255.45	$255.40
Purchase #5	$209.94	9.707%	$230.3189	$230.32	$230.30	$230.30
Purchase #6	$85.39	4.800%	$89.4887	$89.49	$89.50	$89.50
Purchase #7	$59.91	8.297%	$64.8807	$64.88	$64.90	$64.90
7 purchase totals =	$1,035.02		$1,118.2993	$1,118.30	$1,118.35	$1,118.30