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	$81.87	4.166%	$85.2807	$85.28	$85.30	$85.30
Purchase #2	$95.65	4.303%	$99.7658	$99.77	$99.75	$99.80
Purchase #3	$141.68	7.787%	$152.7126	$152.71	$152.70	$152.70
Purchase #4	$176.25	9.435%	$192.8792	$192.88	$192.90	$192.90
Purchase #5	$210.55	7.550%	$226.4465	$226.45	$226.45	$226.40
Purchase #6	$186.92	7.235%	$200.4437	$200.44	$200.45	$200.40
Purchase #7	$74.79	4.154%	$77.8968	$77.90	$77.90	$77.90
7 purchase totals =	$967.71		$1,035.4253	$1,035.43	$1,035.45	$1,035.40