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	$84.55	8.761%	$91.9574	$91.96	$91.95	$92.00
Purchase #2	$128.60	4.339%	$134.18	$134.18	$134.20	$134.20
Purchase #3	$228.66	6.398%	$243.2897	$243.29	$243.30	$243.30
Purchase #4	$139.87	7.671%	$150.5994	$150.60	$150.60	$150.60
Purchase #5	$35.91	12.658%	$40.4555	$40.46	$40.45	$40.50
Purchase #6	$196.94	6.512%	$209.7647	$209.76	$209.75	$209.80
Purchase #7	$179.35	4.767%	$187.8996	$187.90	$187.90	$187.90
7 purchase totals =	$993.88		$1,058.1463	$1,058.15	$1,058.15	$1,058.30