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	$65.27	9.156%	$71.2461	$71.25	$71.25	$71.20
Purchase #2	$59.96	4.327%	$62.5545	$62.55	$62.55	$62.60
Purchase #3	$227.98	13.387%	$258.4997	$258.50	$258.50	$258.50
Purchase #4	$132.74	5.687%	$140.2889	$140.29	$140.30	$140.30
Purchase #5	$238.28	6.799%	$254.4807	$254.48	$254.50	$254.50
Purchase #6	$123.75	10.114%	$136.2661	$136.27	$136.25	$136.30
Purchase #7	$130.35	6.467%	$138.7797	$138.78	$138.80	$138.80
7 purchase totals =	$978.33		$1,062.1157	$1,062.12	$1,062.15	$1,062.20