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	$233.82	4.639%	$244.6669	$244.67	$244.65	$244.70
Purchase #2	$64.27	4.465%	$67.1397	$67.14	$67.15	$67.10
Purchase #3	$66.37	8.486%	$72.0022	$72.00	$72.00	$72.00
Purchase #4	$142.29	9.203%	$155.3849	$155.38	$155.40	$155.40
Purchase #5	$76.44	13.423%	$86.7005	$86.70	$86.70	$86.70
Purchase #6	$241.46	5.238%	$254.1077	$254.11	$254.10	$254.10
Purchase #7	$159.95	12.773%	$180.3804	$180.38	$180.40	$180.40
7 purchase totals =	$984.60		$1,060.3823	$1,060.38	$1,060.40	$1,060.40