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	$174.63	5.635%	$184.4704	$184.47	$184.45	$184.50
Purchase #2	$159.85	4.467%	$166.9905	$166.99	$167.00	$167.00
Purchase #3	$87.45	5.775%	$92.5002	$92.50	$92.50	$92.50
Purchase #4	$106.38	13.112%	$120.3285	$120.33	$120.35	$120.30
Purchase #5	$235.41	12.518%	$264.8786	$264.88	$264.90	$264.90
Purchase #6	$123.29	3.189%	$127.2217	$127.22	$127.20	$127.20
Purchase #7	$156.88	11.329%	$174.6529	$174.65	$174.65	$174.70
7 purchase totals =	$1,043.89		$1,131.0428	$1,131.04	$1,131.05	$1,131.10