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	$91.58	3.792%	$95.0527	$95.05	$95.05	$95.10
Purchase #2	$164.88	12.278%	$185.124	$185.12	$185.10	$185.10
Purchase #3	$237.29	13.214%	$268.6455	$268.65	$268.65	$268.60
Purchase #4	$230.86	6.697%	$246.3207	$246.32	$246.30	$246.30
Purchase #5	$90.70	13.567%	$103.0053	$103.01	$103.00	$103.00
Purchase #6	$94.60	11.320%	$105.3087	$105.31	$105.30	$105.30
Purchase #7	$5.84	7.482%	$6.2769	$6.28	$6.30	$6.30
7 purchase totals =	$915.75		$1,009.7338	$1,009.74	$1,009.70	$1,009.70