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	$112.74	3.134%	$116.2733	$116.27	$116.25	$116.30
Purchase #2	$226.34	12.798%	$255.307	$255.31	$255.30	$255.30
Purchase #3	$62.54	3.581%	$64.7796	$64.78	$64.80	$64.80
Purchase #4	$177.64	4.168%	$185.044	$185.04	$185.05	$185.00
Purchase #5	$64.45	9.175%	$70.3633	$70.36	$70.35	$70.40
Purchase #6	$138.55	8.460%	$150.2713	$150.27	$150.25	$150.30
Purchase #7	$193.52	5.661%	$204.4752	$204.48	$204.50	$204.50
7 purchase totals =	$975.78		$1,046.5137	$1,046.51	$1,046.50	$1,046.60