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	$190.90	7.505%	$205.227	$205.23	$205.25	$205.20
Purchase #2	$206.66	4.566%	$216.0961	$216.10	$216.10	$216.10
Purchase #3	$43.61	4.161%	$45.4246	$45.42	$45.40	$45.40
Purchase #4	$167.56	6.274%	$178.0727	$178.07	$178.05	$178.10
Purchase #5	$152.26	10.288%	$167.9245	$167.92	$167.90	$167.90
Purchase #6	$173.27	8.156%	$187.4019	$187.40	$187.40	$187.40
Purchase #7	$178.85	3.850%	$185.7357	$185.74	$185.75	$185.70
7 purchase totals =	$1,113.11		$1,185.8825	$1,185.88	$1,185.85	$1,185.80