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	$195.75	7.470%	$210.3725	$210.37	$210.35	$210.40
Purchase #2	$69.31	10.251%	$76.415	$76.42	$76.40	$76.40
Purchase #3	$109.98	3.531%	$113.8634	$113.86	$113.85	$113.90
Purchase #4	$65.61	7.228%	$70.3523	$70.35	$70.35	$70.40
Purchase #5	$79.25	12.598%	$89.2339	$89.23	$89.25	$89.20
Purchase #6	$196.96	10.368%	$217.3808	$217.38	$217.40	$217.40
Purchase #7	$217.77	10.324%	$240.2526	$240.25	$240.25	$240.30
7 purchase totals =	$934.63		$1,017.8705	$1,017.86	$1,017.85	$1,018.00