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	$179.25	7.450%	$192.6041	$192.60	$192.60	$192.60
Purchase #2	$39.57	9.449%	$43.309	$43.31	$43.30	$43.30
Purchase #3	$30.40	9.124%	$33.1737	$33.17	$33.15	$33.20
Purchase #4	$73.31	3.435%	$75.8282	$75.83	$75.85	$75.80
Purchase #5	$233.39	7.146%	$250.068	$250.07	$250.05	$250.10
Purchase #6	$236.59	7.867%	$255.2025	$255.20	$255.20	$255.20
Purchase #7	$241.58	5.735%	$255.4346	$255.43	$255.45	$255.40
7 purchase totals =	$1,034.09		$1,105.6201	$1,105.61	$1,105.60	$1,105.60