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	$94.49	7.320%	$101.4067	$101.41	$101.40	$101.40
Purchase #2	$226.33	8.578%	$245.7446	$245.74	$245.75	$245.70
Purchase #3	$171.62	8.105%	$185.5298	$185.53	$185.55	$185.50
Purchase #4	$137.87	6.259%	$146.4993	$146.50	$146.50	$146.50
Purchase #5	$74.89	11.871%	$83.7802	$83.78	$83.80	$83.80
Purchase #6	$191.56	11.474%	$213.5396	$213.54	$213.55	$213.50
Purchase #7	$44.59	9.543%	$48.8452	$48.85	$48.85	$48.80
7 purchase totals =	$941.35		$1,025.3454	$1,025.35	$1,025.40	$1,025.20