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	$185.75	5.235%	$195.474	$195.47	$195.45	$195.50
Purchase #2	$103.31	3.672%	$107.1035	$107.10	$107.10	$107.10
Purchase #3	$161.88	8.173%	$175.1105	$175.11	$175.10	$175.10
Purchase #4	$91.55	10.208%	$100.8954	$100.90	$100.90	$100.90
Purchase #5	$100.95	11.260%	$112.317	$112.32	$112.30	$112.30
Purchase #6	$71.28	9.662%	$78.1671	$78.17	$78.15	$78.20
Purchase #7	$224.48	10.805%	$248.7351	$248.74	$248.75	$248.70
7 purchase totals =	$939.20		$1,017.8026	$1,017.81	$1,017.75	$1,017.80