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	$196.83	8.628%	$213.8125	$213.81	$213.80	$213.80
Purchase #2	$171.46	6.605%	$182.7849	$182.78	$182.80	$182.80
Purchase #3	$216.93	11.568%	$242.0245	$242.02	$242.00	$242.00
Purchase #4	$96.37	9.437%	$105.4644	$105.46	$105.45	$105.50
Purchase #5	$237.42	7.150%	$254.3955	$254.40	$254.40	$254.40
Purchase #6	$37.75	12.704%	$42.5458	$42.55	$42.55	$42.50
Purchase #7	$196.75	9.425%	$215.2937	$215.29	$215.30	$215.30
7 purchase totals =	$1,153.51		$1,256.3213	$1,256.31	$1,256.30	$1,256.30