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	$146.94	10.765%	$162.7581	$162.76	$162.75	$162.80
Purchase #2	$70.85	4.778%	$74.2352	$74.24	$74.25	$74.20
Purchase #3	$21.47	3.165%	$22.1495	$22.15	$22.15	$22.10
Purchase #4	$36.43	11.321%	$40.5542	$40.55	$40.55	$40.60
Purchase #5	$32.53	9.651%	$35.6695	$35.67	$35.65	$35.70
Purchase #6	$59.36	8.470%	$64.3878	$64.39	$64.40	$64.40
Purchase #7	$41.31	10.269%	$45.5521	$45.55	$45.55	$45.60
7 purchase totals =	$408.89		$445.3064	$445.31	$445.30	$445.40