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	$237.36	10.554%	$262.411	$262.41	$262.40	$262.40
Purchase #2	$37.92	11.347%	$42.2228	$42.22	$42.20	$42.20
Purchase #3	$184.27	9.774%	$202.2805	$202.28	$202.30	$202.30
Purchase #4	$125.52	12.405%	$141.0908	$141.09	$141.10	$141.10
Purchase #5	$218.81	13.354%	$248.0299	$248.03	$248.05	$248.00
Purchase #6	$115.75	13.445%	$131.3126	$131.31	$131.30	$131.30
Purchase #7	$123.76	3.813%	$128.479	$128.48	$128.50	$128.50
7 purchase totals =	$1,043.39		$1,155.8266	$1,155.82	$1,155.85	$1,155.80