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	$147.52	7.479%	$158.553	$158.55	$158.55	$158.60
Purchase #2	$205.57	7.740%	$221.4811	$221.48	$221.50	$221.50
Purchase #3	$50.86	7.212%	$54.528	$54.53	$54.55	$54.50
Purchase #4	$204.31	7.746%	$220.1359	$220.14	$220.15	$220.10
Purchase #5	$103.72	6.714%	$110.6838	$110.68	$110.70	$110.70
Purchase #6	$160.70	5.555%	$169.6269	$169.63	$169.65	$169.60
Purchase #7	$124.57	5.428%	$131.3317	$131.33	$131.35	$131.30
7 purchase totals =	$997.25		$1,066.3404	$1,066.34	$1,066.45	$1,066.30