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	$155.82	4.412%	$162.6948	$162.69	$162.70	$162.70
Purchase #2	$200.27	13.470%	$227.2464	$227.25	$227.25	$227.20
Purchase #3	$13.43	5.568%	$14.1778	$14.18	$14.20	$14.20
Purchase #4	$150.95	3.712%	$156.5533	$156.55	$156.55	$156.60
Purchase #5	$207.45	7.676%	$223.3739	$223.37	$223.35	$223.40
Purchase #6	$33.36	10.260%	$36.7827	$36.78	$36.80	$36.80
Purchase #7	$205.49	13.524%	$233.2805	$233.28	$233.30	$233.30
7 purchase totals =	$966.77		$1,054.1094	$1,054.10	$1,054.15	$1,054.20