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	$177.42	7.245%	$190.2741	$190.27	$190.25	$190.30
Purchase #2	$135.75	8.667%	$147.5155	$147.52	$147.50	$147.50
Purchase #3	$73.42	6.629%	$78.287	$78.29	$78.30	$78.30
Purchase #4	$142.69	5.332%	$150.2982	$150.30	$150.30	$150.30
Purchase #5	$190.60	11.523%	$212.5628	$212.56	$212.55	$212.60
Purchase #6	$13.38	4.848%	$14.0287	$14.03	$14.05	$14.00
Purchase #7	$243.29	10.500%	$268.8355	$268.84	$268.85	$268.80
7 purchase totals =	$976.55		$1,061.8018	$1,061.81	$1,061.80	$1,061.80