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	$217.77	11.331%	$242.4455	$242.45	$242.45	$242.40
Purchase #2	$170.25	5.611%	$179.8027	$179.80	$179.80	$179.80
Purchase #3	$223.41	11.179%	$248.385	$248.39	$248.40	$248.40
Purchase #4	$225.29	11.690%	$251.6264	$251.63	$251.65	$251.60
Purchase #5	$141.57	4.524%	$147.9746	$147.97	$147.95	$148.00
Purchase #6	$86.60	4.440%	$90.445	$90.45	$90.45	$90.40
Purchase #7	$191.50	10.776%	$212.136	$212.14	$212.15	$212.10
7 purchase totals =	$1,256.39		$1,372.8152	$1,372.83	$1,372.85	$1,372.70