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	$230.94	5.357%	$243.3115	$243.31	$243.30	$243.30
Purchase #2	$156.78	10.570%	$173.3516	$173.35	$173.35	$173.40
Purchase #3	$17.69	9.553%	$19.3799	$19.38	$19.40	$19.40
Purchase #4	$179.78	3.743%	$186.5092	$186.51	$186.50	$186.50
Purchase #5	$77.92	10.738%	$86.287	$86.29	$86.30	$86.30
Purchase #6	$180.28	6.650%	$192.2686	$192.27	$192.25	$192.30
Purchase #7	$145.79	5.234%	$153.4206	$153.42	$153.40	$153.40
7 purchase totals =	$989.18		$1,054.5284	$1,054.53	$1,054.50	$1,054.60