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	$164.69	5.705%	$174.0856	$174.09	$174.10	$174.10
Purchase #2	$145.28	13.571%	$164.9959	$165.00	$165.00	$165.00
Purchase #3	$48.93	6.566%	$52.1427	$52.14	$52.15	$52.10
Purchase #4	$98.59	6.668%	$105.164	$105.16	$105.15	$105.20
Purchase #5	$204.44	8.352%	$221.5148	$221.51	$221.50	$221.50
Purchase #6	$119.93	6.164%	$127.3225	$127.32	$127.30	$127.30
Purchase #7	$204.68	8.632%	$222.348	$222.35	$222.35	$222.30
7 purchase totals =	$986.54		$1,067.5735	$1,067.57	$1,067.55	$1,067.50