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	$125.54	7.398%	$134.8274	$134.83	$134.85	$134.80
Purchase #2	$27.63	4.432%	$28.8546	$28.85	$28.85	$28.90
Purchase #3	$227.53	9.170%	$248.3945	$248.39	$248.40	$248.40
Purchase #4	$99.39	6.780%	$106.1286	$106.13	$106.15	$106.10
Purchase #5	$184.99	10.828%	$205.0207	$205.02	$205.00	$205.00
Purchase #6	$175.84	3.612%	$182.1913	$182.19	$182.20	$182.20
Purchase #7	$98.26	13.124%	$111.1556	$111.16	$111.15	$111.20
7 purchase totals =	$939.18		$1,016.5727	$1,016.57	$1,016.60	$1,016.60