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	$161.63	10.315%	$178.3021	$178.30	$178.30	$178.30
Purchase #2	$14.46	4.776%	$15.1506	$15.15	$15.15	$15.20
Purchase #3	$85.46	13.846%	$97.2928	$97.29	$97.30	$97.30
Purchase #4	$249.54	8.325%	$270.3142	$270.31	$270.30	$270.30
Purchase #5	$192.37	9.109%	$209.893	$209.89	$209.90	$209.90
Purchase #6	$142.54	6.687%	$152.0716	$152.07	$152.05	$152.10
Purchase #7	$89.33	12.369%	$100.3792	$100.38	$100.40	$100.40
7 purchase totals =	$935.33		$1,023.4035	$1,023.39	$1,023.40	$1,023.50