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	$143.29	3.245%	$147.9398	$147.94	$147.95	$147.90
Purchase #2	$205.78	5.177%	$216.4332	$216.43	$216.45	$216.40
Purchase #3	$201.67	4.764%	$211.2776	$211.28	$211.30	$211.30
Purchase #4	$200.51	4.607%	$209.7475	$209.75	$209.75	$209.70
Purchase #5	$226.94	12.506%	$255.3211	$255.32	$255.30	$255.30
Purchase #6	$50.81	4.540%	$53.1168	$53.12	$53.10	$53.10
Purchase #7	$47.46	12.370%	$53.3308	$53.33	$53.35	$53.30
7 purchase totals =	$1,076.46		$1,147.1668	$1,147.17	$1,147.20	$1,147.00