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	$184.68	6.251%	$196.2243	$196.22	$196.20	$196.20
Purchase #2	$219.55	11.229%	$244.2033	$244.20	$244.20	$244.20
Purchase #3	$94.38	4.217%	$98.36	$98.36	$98.35	$98.40
Purchase #4	$76.39	12.751%	$86.1305	$86.13	$86.15	$86.10
Purchase #5	$173.52	11.170%	$192.9022	$192.90	$192.90	$192.90
Purchase #6	$145.31	5.695%	$153.5854	$153.59	$153.60	$153.60
Purchase #7	$123.31	13.640%	$140.1295	$140.13	$140.15	$140.10
7 purchase totals =	$1,017.14		$1,111.5352	$1,111.53	$1,111.55	$1,111.50