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	$207.56	7.593%	$223.32	$223.32	$223.30	$223.30
Purchase #2	$197.41	6.501%	$210.2436	$210.24	$210.25	$210.20
Purchase #3	$161.67	6.685%	$172.4776	$172.48	$172.50	$172.50
Purchase #4	$131.25	4.838%	$137.5999	$137.60	$137.60	$137.60
Purchase #5	$95.35	3.744%	$98.9199	$98.92	$98.90	$98.90
Purchase #6	$167.77	3.144%	$173.0447	$173.04	$173.05	$173.00
Purchase #7	$17.85	7.407%	$19.1721	$19.17	$19.15	$19.20
7 purchase totals =	$978.86		$1,034.7778	$1,034.77	$1,034.75	$1,034.70