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	$90.88	5.482%	$95.862	$95.86	$95.85	$95.90
Purchase #2	$173.46	12.129%	$194.499	$194.50	$194.50	$194.50
Purchase #3	$244.82	8.445%	$265.495	$265.50	$265.50	$265.50
Purchase #4	$43.36	4.296%	$45.2227	$45.22	$45.20	$45.20
Purchase #5	$35.92	12.625%	$40.4549	$40.45	$40.45	$40.50
Purchase #6	$165.93	13.515%	$188.3554	$188.36	$188.35	$188.40
Purchase #7	$65.77	8.315%	$71.2388	$71.24	$71.25	$71.20
7 purchase totals =	$820.14		$901.1278	$901.13	$901.10	$901.20