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	$213.75	3.338%	$220.885	$220.89	$220.90	$220.90
Purchase #2	$72.56	12.256%	$81.453	$81.45	$81.45	$81.50
Purchase #3	$218.76	11.649%	$244.2434	$244.24	$244.25	$244.20
Purchase #4	$182.50	4.692%	$191.0629	$191.06	$191.05	$191.10
Purchase #5	$197.80	9.338%	$216.2706	$216.27	$216.25	$216.30
Purchase #6	$36.42	11.498%	$40.6076	$40.61	$40.60	$40.60
Purchase #7	$98.82	11.736%	$110.4175	$110.42	$110.40	$110.40
7 purchase totals =	$1,020.61		$1,104.9400	$1,104.94	$1,104.90	$1,105.00