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	$196.70	11.252%	$218.8327	$218.83	$218.85	$218.80
Purchase #2	$223.56	3.170%	$230.6469	$230.65	$230.65	$230.60
Purchase #3	$170.90	10.316%	$188.53	$188.53	$188.55	$188.50
Purchase #4	$195.74	5.525%	$206.5546	$206.55	$206.55	$206.60
Purchase #5	$5.92	10.307%	$6.5302	$6.53	$6.55	$6.50
Purchase #6	$114.68	10.782%	$127.0448	$127.04	$127.05	$127.00
Purchase #7	$41.42	9.765%	$45.4647	$45.46	$45.45	$45.50
7 purchase totals =	$948.92		$1,023.6039	$1,023.59	$1,023.65	$1,023.50