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	$55.79	11.867%	$62.4106	$62.41	$62.40	$62.40
Purchase #2	$145.92	9.867%	$160.3179	$160.32	$160.30	$160.30
Purchase #3	$192.54	3.792%	$199.8411	$199.84	$199.85	$199.80
Purchase #4	$196.27	12.369%	$220.5466	$220.55	$220.55	$220.50
Purchase #5	$103.53	4.445%	$108.1319	$108.13	$108.15	$108.10
Purchase #6	$189.70	3.562%	$196.4571	$196.46	$196.45	$196.50
Purchase #7	$115.94	3.871%	$120.428	$120.43	$120.45	$120.40
7 purchase totals =	$999.69		$1,068.1332	$1,068.14	$1,068.15	$1,068.00