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	$174.92	12.240%	$196.3302	$196.33	$196.35	$196.30
Purchase #2	$145.46	11.606%	$162.3421	$162.34	$162.35	$162.30
Purchase #3	$88.60	6.771%	$94.5991	$94.60	$94.60	$94.60
Purchase #4	$137.39	7.256%	$147.359	$147.36	$147.35	$147.40
Purchase #5	$188.25	12.795%	$212.3366	$212.34	$212.35	$212.30
Purchase #6	$93.93	13.849%	$106.9384	$106.94	$106.95	$106.90
Purchase #7	$121.52	5.168%	$127.8002	$127.80	$127.80	$127.80
7 purchase totals =	$950.07		$1,047.7056	$1,047.71	$1,047.75	$1,047.60