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	$125.76	4.824%	$131.8267	$131.83	$131.85	$131.80
Purchase #2	$209.35	8.151%	$226.4141	$226.41	$226.40	$226.40
Purchase #3	$184.52	11.498%	$205.7361	$205.74	$205.75	$205.70
Purchase #4	$177.60	10.692%	$196.589	$196.59	$196.60	$196.60
Purchase #5	$199.93	5.608%	$211.1421	$211.14	$211.15	$211.10
Purchase #6	$141.69	7.694%	$152.5916	$152.59	$152.60	$152.60
Purchase #7	$142.79	13.367%	$161.8767	$161.88	$161.90	$161.90
7 purchase totals =	$1,181.64		$1,286.1763	$1,286.18	$1,286.25	$1,286.10