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	$163.89	3.445%	$169.536	$169.54	$169.55	$169.50
Purchase #2	$70.99	7.714%	$76.4662	$76.47	$76.45	$76.50
Purchase #3	$228.34	6.439%	$243.0428	$243.04	$243.05	$243.00
Purchase #4	$156.32	9.613%	$171.347	$171.35	$171.35	$171.30
Purchase #5	$101.56	8.102%	$109.7884	$109.79	$109.80	$109.80
Purchase #6	$78.71	5.229%	$82.8257	$82.83	$82.85	$82.80
Purchase #7	$163.29	3.413%	$168.8631	$168.86	$168.85	$168.90
7 purchase totals =	$963.10		$1,021.8692	$1,021.88	$1,021.90	$1,021.80