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	$182.76	4.540%	$191.0573	$191.06	$191.05	$191.10
Purchase #2	$217.73	7.372%	$233.7811	$233.78	$233.80	$233.80
Purchase #3	$189.91	3.373%	$196.3157	$196.32	$196.30	$196.30
Purchase #4	$192.71	13.432%	$218.5948	$218.59	$218.60	$218.60
Purchase #5	$41.71	3.659%	$43.2362	$43.24	$43.25	$43.20
Purchase #6	$6.78	7.290%	$7.2743	$7.27	$7.25	$7.30
Purchase #7	$250.49	4.427%	$261.5792	$261.58	$261.60	$261.60
7 purchase totals =	$1,082.09		$1,151.8386	$1,151.84	$1,151.85	$1,151.90