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	$142.39	7.130%	$152.5424	$152.54	$152.55	$152.50
Purchase #2	$6.96	9.375%	$7.6125	$7.61	$7.60	$7.60
Purchase #3	$43.56	9.615%	$47.7483	$47.75	$47.75	$47.70
Purchase #4	$128.80	9.843%	$141.4778	$141.48	$141.50	$141.50
Purchase #5	$95.87	8.382%	$103.9058	$103.91	$103.90	$103.90
Purchase #6	$163.88	13.651%	$186.2513	$186.25	$186.25	$186.30
Purchase #7	$165.59	11.641%	$184.8663	$184.87	$184.85	$184.90
7 purchase totals =	$747.05		$824.4044	$824.41	$824.40	$824.40