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	$194.83	7.450%	$209.3448	$209.34	$209.35	$209.30
Purchase #2	$96.94	6.624%	$103.3613	$103.36	$103.35	$103.40
Purchase #3	$69.68	3.506%	$72.123	$72.12	$72.10	$72.10
Purchase #4	$34.94	13.365%	$39.6097	$39.61	$39.60	$39.60
Purchase #5	$182.66	12.175%	$204.8989	$204.90	$204.90	$204.90
Purchase #6	$155.42	13.114%	$175.8018	$175.80	$175.80	$175.80
Purchase #7	$124.86	13.805%	$142.0969	$142.10	$142.10	$142.10
7 purchase totals =	$859.33		$947.2364	$947.23	$947.20	$947.20