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	$118.94	7.350%	$127.6821	$127.68	$127.70	$127.70
Purchase #2	$194.83	4.351%	$203.3071	$203.31	$203.30	$203.30
Purchase #3	$34.59	3.470%	$35.7903	$35.79	$35.80	$35.80
Purchase #4	$123.74	6.189%	$131.3983	$131.40	$131.40	$131.40
Purchase #5	$86.53	11.478%	$96.4619	$96.46	$96.45	$96.50
Purchase #6	$153.52	11.594%	$171.3191	$171.32	$171.30	$171.30
Purchase #7	$163.26	9.795%	$179.2513	$179.25	$179.25	$179.30
7 purchase totals =	$875.41		$945.2101	$945.21	$945.20	$945.30