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	$181.56	7.611%	$195.3785	$195.38	$195.40	$195.40
Purchase #2	$183.92	12.187%	$206.3343	$206.33	$206.35	$206.30
Purchase #3	$40.61	11.492%	$45.2769	$45.28	$45.30	$45.30
Purchase #4	$130.77	7.385%	$140.4274	$140.43	$140.45	$140.40
Purchase #5	$241.49	12.133%	$270.79	$270.79	$270.80	$270.80
Purchase #6	$56.89	10.565%	$62.9004	$62.90	$62.90	$62.90
Purchase #7	$123.27	8.709%	$134.0056	$134.01	$134.00	$134.00
7 purchase totals =	$958.51		$1,055.1131	$1,055.12	$1,055.20	$1,055.10