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	$118.99	7.523%	$127.9416	$127.94	$127.95	$127.90
Purchase #2	$83.51	13.129%	$94.474	$94.47	$94.45	$94.50
Purchase #3	$210.46	4.254%	$219.413	$219.41	$219.40	$219.40
Purchase #4	$100.52	9.460%	$110.0292	$110.03	$110.05	$110.00
Purchase #5	$174.33	12.693%	$196.4577	$196.46	$196.45	$196.50
Purchase #6	$238.27	5.608%	$251.6322	$251.63	$251.65	$251.60
Purchase #7	$52.84	6.761%	$56.4125	$56.41	$56.40	$56.40
7 purchase totals =	$978.92		$1,056.3602	$1,056.35	$1,056.35	$1,056.30