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	$54.26	13.583%	$61.6301	$61.63	$61.65	$61.60
Purchase #2	$180.39	6.132%	$191.4515	$191.45	$191.45	$191.50
Purchase #3	$133.57	6.406%	$142.1265	$142.13	$142.15	$142.10
Purchase #4	$76.43	11.780%	$85.4335	$85.43	$85.45	$85.40
Purchase #5	$212.93	9.331%	$232.7985	$232.80	$232.80	$232.80
Purchase #6	$211.74	5.718%	$223.8473	$223.85	$223.85	$223.80
Purchase #7	$147.25	11.303%	$163.8937	$163.89	$163.90	$163.90
7 purchase totals =	$1,016.57		$1,101.1811	$1,101.18	$1,101.25	$1,101.10