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	$179.41	9.270%	$196.0413	$196.04	$196.05	$196.00
Purchase #2	$200.91	6.331%	$213.6296	$213.63	$213.65	$213.60
Purchase #3	$88.91	12.850%	$100.3349	$100.33	$100.35	$100.30
Purchase #4	$84.63	7.556%	$91.0246	$91.02	$91.00	$91.00
Purchase #5	$30.32	7.402%	$32.5643	$32.56	$32.55	$32.60
Purchase #6	$211.33	7.764%	$227.7377	$227.74	$227.75	$227.70
Purchase #7	$110.37	3.711%	$114.4658	$114.47	$114.45	$114.50
7 purchase totals =	$905.88		$975.7982	$975.79	$975.80	$975.70