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	$189.60	5.703%	$200.4129	$200.41	$200.40	$200.40
Purchase #2	$68.97	3.387%	$71.306	$71.31	$71.30	$71.30
Purchase #3	$174.60	3.618%	$180.917	$180.92	$180.90	$180.90
Purchase #4	$156.59	9.414%	$171.3314	$171.33	$171.35	$171.30
Purchase #5	$71.75	9.168%	$78.328	$78.33	$78.35	$78.30
Purchase #6	$116.88	3.631%	$121.1239	$121.12	$121.10	$121.10
Purchase #7	$201.84	5.556%	$213.0542	$213.05	$213.05	$213.10
7 purchase totals =	$980.23		$1,036.4734	$1,036.47	$1,036.45	$1,036.40