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	$125.63	13.717%	$142.8627	$142.86	$142.85	$142.90
Purchase #2	$88.36	4.263%	$92.1268	$92.13	$92.15	$92.10
Purchase #3	$143.38	9.275%	$156.6785	$156.68	$156.70	$156.70
Purchase #4	$168.28	6.252%	$178.8009	$178.80	$178.80	$178.80
Purchase #5	$118.80	4.190%	$123.7777	$123.78	$123.80	$123.80
Purchase #6	$185.37	5.862%	$196.2364	$196.24	$196.25	$196.20
Purchase #7	$142.28	7.404%	$152.8144	$152.81	$152.80	$152.80
7 purchase totals =	$972.10		$1,043.2974	$1,043.30	$1,043.35	$1,043.30