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	$182.29	10.419%	$201.2828	$201.28	$201.30	$201.30
Purchase #2	$147.79	3.175%	$152.4823	$152.48	$152.50	$152.50
Purchase #3	$96.55	13.802%	$109.8758	$109.88	$109.90	$109.90
Purchase #4	$103.36	7.660%	$111.2774	$111.28	$111.30	$111.30
Purchase #5	$176.35	8.841%	$191.9411	$191.94	$191.95	$191.90
Purchase #6	$83.29	9.723%	$91.3883	$91.39	$91.40	$91.40
Purchase #7	$177.90	7.425%	$191.1091	$191.11	$191.10	$191.10
7 purchase totals =	$967.53		$1,049.3568	$1,049.36	$1,049.45	$1,049.40