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	$85.80	11.261%	$95.4619	$95.46	$95.45	$95.50
Purchase #2	$221.63	9.391%	$242.4433	$242.44	$242.45	$242.40
Purchase #3	$18.75	13.697%	$21.3182	$21.32	$21.30	$21.30
Purchase #4	$243.80	8.435%	$264.3645	$264.36	$264.35	$264.40
Purchase #5	$14.55	4.860%	$15.2571	$15.26	$15.25	$15.30
Purchase #6	$200.35	9.431%	$219.245	$219.25	$219.25	$219.20
Purchase #7	$168.32	12.144%	$188.7608	$188.76	$188.75	$188.80
7 purchase totals =	$953.20		$1,046.8508	$1,046.85	$1,046.80	$1,046.90