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	$135.96	11.830%	$152.0441	$152.04	$152.05	$152.00
Purchase #2	$14.51	10.647%	$16.0549	$16.05	$16.05	$16.10
Purchase #3	$58.58	7.434%	$62.9348	$62.93	$62.95	$62.90
Purchase #4	$244.58	8.543%	$265.4745	$265.47	$265.45	$265.50
Purchase #5	$86.27	3.310%	$89.1255	$89.13	$89.15	$89.10
Purchase #6	$161.99	10.109%	$178.3656	$178.37	$178.35	$178.40
Purchase #7	$247.69	13.861%	$282.0223	$282.02	$282.00	$282.00
7 purchase totals =	$949.58		$1,046.0217	$1,046.01	$1,046.00	$1,046.00