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	$228.27	11.333%	$254.1398	$254.14	$254.15	$254.10
Purchase #2	$91.61	9.379%	$100.2021	$100.20	$100.20	$100.20
Purchase #3	$42.79	11.414%	$47.6741	$47.67	$47.65	$47.70
Purchase #4	$38.48	10.349%	$42.4623	$42.46	$42.45	$42.50
Purchase #5	$102.49	8.299%	$110.9956	$111.00	$111.00	$111.00
Purchase #6	$167.29	4.259%	$174.4149	$174.41	$174.40	$174.40
Purchase #7	$191.34	13.702%	$217.5574	$217.56	$217.55	$217.60
7 purchase totals =	$862.27		$947.4462	$947.44	$947.40	$947.50