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	$97.65	7.168%	$104.6496	$104.65	$104.65	$104.60
Purchase #2	$211.39	4.458%	$220.8138	$220.81	$220.80	$220.80
Purchase #3	$72.81	4.854%	$76.3442	$76.34	$76.35	$76.30
Purchase #4	$174.37	6.372%	$185.4809	$185.48	$185.50	$185.50
Purchase #5	$81.83	5.596%	$86.4092	$86.41	$86.40	$86.40
Purchase #6	$233.82	12.503%	$263.0545	$263.05	$263.05	$263.10
Purchase #7	$97.85	12.168%	$109.7564	$109.76	$109.75	$109.80
7 purchase totals =	$969.72		$1,046.5086	$1,046.50	$1,046.50	$1,046.50