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	$225.72	11.217%	$251.039	$251.04	$251.05	$251.00
Purchase #2	$146.53	10.761%	$162.2981	$162.30	$162.30	$162.30
Purchase #3	$189.72	7.753%	$204.429	$204.43	$204.45	$204.40
Purchase #4	$160.57	11.850%	$179.5975	$179.60	$179.60	$179.60
Purchase #5	$13.30	7.786%	$14.3355	$14.34	$14.35	$14.30
Purchase #6	$166.58	3.791%	$172.895	$172.90	$172.90	$172.90
Purchase #7	$156.91	9.573%	$171.931	$171.93	$171.95	$171.90
7 purchase totals =	$1,059.33		$1,156.5251	$1,156.54	$1,156.60	$1,156.40