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	$85.84	10.417%	$94.782	$94.78	$94.80	$94.80
Purchase #2	$114.87	8.729%	$124.897	$124.90	$124.90	$124.90
Purchase #3	$179.32	9.380%	$196.1402	$196.14	$196.15	$196.10
Purchase #4	$165.52	12.447%	$186.1223	$186.12	$186.10	$186.10
Purchase #5	$14.47	6.259%	$15.3757	$15.38	$15.40	$15.40
Purchase #6	$55.43	10.630%	$61.3222	$61.32	$61.30	$61.30
Purchase #7	$15.84	4.139%	$16.4956	$16.50	$16.50	$16.50
7 purchase totals =	$631.29		$695.1350	$695.14	$695.15	$695.10