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	$250.90	4.813%	$262.9758	$262.98	$263.00	$263.00
Purchase #2	$239.84	4.764%	$251.266	$251.27	$251.25	$251.30
Purchase #3	$28.70	9.280%	$31.3634	$31.36	$31.35	$31.40
Purchase #4	$173.78	4.423%	$181.4663	$181.47	$181.45	$181.50
Purchase #5	$94.90	12.196%	$106.474	$106.47	$106.45	$106.50
Purchase #6	$219.71	8.563%	$238.5238	$238.52	$238.50	$238.50
Purchase #7	$26.48	9.216%	$28.9204	$28.92	$28.90	$28.90
7 purchase totals =	$1,034.31		$1,100.9897	$1,100.99	$1,100.90	$1,101.10